Factors influencing maternal positions during labor
Posted April 2010
Maternal body positions have a significant influence on the course of labor, affecting maternal comfort and maternal and fetal physiology. Upright positions in the first stage are those that avoid lying flat, and can include walking. Upright positions in the second stage include sitting, squatting or kneeling and being on hands and knees. Laboring women who adopt a more upright position for labor experience decreased pain, fewer fetal heart rate abnormalities, a shorter second stage; fewer assisted births and episiotomies; more second degree perineal tears and more blood loss estimated as over 500 ml (Gupta et al., 2004 Soong & Barnes 2005; Stremler et al. 2005; De Jonge, 2007, Lawrence 2009). Midwives and other health care providers have a significant influence on the positions of laboring women, through encouragement and bedside guidance. There is ever increasing medicalization to childbirth; with this trend, women have less choice in positioning options due to anesthesia and monitoring technology constraints. Routine technologic interventions such as electronic fetal
monitoring and epidural anesthesia have altered the course of natural childbirth.
Midwives generally encourage laboring women to be mobile as long as possible and to adopt whatever position is most comfortable, however, there are indications and contraindications for the use of certain positions during the course of labor. Modifying intrapartum care to reflect current evidence, regarding the factors that influence maternal positions in labor will improve the maternity care that women and families receive. Health professionals working in obstetric care need to be aware of the evidence based practice regarding maternal positions in labor to enable women to make informed choices. The conceptual framework guiding this study is kinesthesiology, body position and movement. This inquiry will explore the factors that influence maternal positions during labor.
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Chapter 1: Statement and Significance of the problem.
Introduction to the problem:
Maternal body positions have a significant influence on the course of labor, affecting maternal comfort and physiology. Laboring women who adopt a more upright position for labor experience decreased pain, fewer fetal heart rate abnormalities, a shorter second stage; fewer assisted births and episiotomies; more second degree perineal tears and more blood loss estimated as over 500 ml (Gupta et al., 2004 Soong & Barnes 2005; Stremler et al. 2005; De Jonge, 2007, Lawrence 2009). Upright posture is supported by radiological evidence of increased anterioposterior and transverse pelvic diameters, resulting in an increase in the total outlet in both the squatting and kneeling positions (Gupta et al.2004). Position changes that are consistent with anatomic principles, such as squatting or kneeling positions to enlarge the pelvis, are generally safe and acceptable to women. Laboring women with ultrasound diagnosed OP fetuses demonstrated that periods in the hands and knees position significantly reduced the likelihood of persistent severe back pain and that this position was acceptable to the women (Stremler.et.al, 2005). Benefits and risks of selected maternal positions in labor are listed in table 1.
Routine technologic interventions such as continuous fetal monitoring and epidural analgesia have altered the types of positions a laboring woman can assume (Spiby, 2003). Although midwives tend to encourage women to utilize physiology and gravity to their advantage during labor by encouraging positional changes, the expectations, experience and education of the midwife attending the woman at birth will influence the range of positions they encourage and facilitate women to adopt.
Upright positions in the first stage are those that avoid lying flat, and can include walking. Upright positions in the second stage include sitting, squatting or kneeling and being on hands and knees. Recumbent positions include supine, lateral, lithotomy and semi recumbent with the use of pillows and wedges. The factors that influence maternal positions in labor include health provider preference and training, birthing equipment availability, analgesia choice, fetal monitoring method and nutritional policy in labor. (See table 2)
TABLE 1: Benefits and risks of the upright position for labor and birth
|Increased diameters of pelvic inlet and outlet||Increase in second degree tears|
|Improved uterine contractility||Increase in blood loss >500ml|
|Improved fetal well being||Practitioner resistance|
|Reduced duration of second stage labor||Maternal fatigue|
|Reduction in assisted deliveries||High dose epidural block|
|Reduction in episiotomies|
|Increased feeling of maternal control/ increased partner involvement|
Table 2: Factors that influence maternal positions in labor
|FACTORS THAT INFLUENCE MATERNAL POSITIONS IN LABOR|
|Maternal preference and maternal ability|
|Health provider preference|
|Health provider training|
|Birthing environment (Home, Birthing Center, Hospital)|
|Analgesia choice (epidural, narcotics)|
|Fetal monitoring method |
Women use various positions, supine and non supine, if they are left to choose (De Jonge, 2004). The supine position however has become so common that neither health care workers nor women regard this as an intervention (De Jonge 2004).The common use of interventions and treatments during labor which include use of continuous electronic fetal monitoring, methods of pain relief such as epidural analgesia and intravenous infusions affect a woman’s mobility and use of postural change in labor (Spiby et al. 2003; Declercq et al., 2006).
Other actions such as the environment and views of health practitioners can influence a woman’s choice of labor position. (Albers 2007, Jonge et al 2008). There are significant advantages to assuming an upright position in labor and birth, such as stronger and more efficient uterine contractions aiding cervical dilatation, increased pelvic inlet and outlet diameters and improved uterine contractility. However women often are persuaded to conform to medical procedures. In American culture, the most common image of the laboring woman is on her back in a bed. Women need to be made aware of alternative positions and advantages and disadvantages in order for them to make an informed choice (De Jonge et al., 2008).
Throughout history women in most cultures have used both the upright position and alternative positions to give birth to babies. Not until the advancement of technology, which began in the seventeenth century with the advent of the forceps, did women give birth in the supine position. (Boyle, 2000).The supine position became increasingly popular within Western societies as the standard position during labor. In the early 18 th Century, a prominent French physician, Francois Mauriceau, introduced the supine positions to facilitate the care of women and to enhance obstetric performance and maneuvers, which then became largely adopted throughout western countries (Diaz et al, 1980). In the last century, childbirth has progressively moved from a woman supported experience in the home to a medical intervention within the hospital (Albers 2007).
Scope of the problem:
According to The National Center for Health Statistics a total of 4,317,119 births were registered in the United States in 2007 (NCHS 2007).
Most women have the potential to have a physiologic labor and birth; one that starts and proceeds on its own, without routine use of interventions or drugs (Albers, 2007).
In a survey entitled Listening to Mothers (2006), fifty seven percent reported that they gave birth lying flat on their backs (Declercq et al, 2006). Further research suggests that although upright positions may be difficult after certain pain relief administration, upright positions could still be achieved with the use of lower dose epidurals (Suplee & Gennaro 2003). Women in labor typically enter an unfamiliar, busy institutional setting to receive care from an array of strangers where numerous technical care measures are routinely used, such as continuous electronic fetal monitoring and epidural anesthesia. In 2002, a national sample of 1583 recently delivered women reported their experiences with health care during maternity care. A full 93% reported having had electronic fetal monitoring; while 71% labored in bed (Declercq, 2002).Intravenous infusion during labor has become a routine procedure for a high percentage of women in labor throughout the United States, these procedures may affect a woman’s mobility and use of postural coping strategies in labor (Spiby et al., 2003).
Significance to women’s health:
Factors such as the ability to maintain some level of autonomy, ability to mobilize and change positions unprompted, in an environment conducive to welcoming partners and family members are important contributors to patient satisfaction. Patient satisfaction plays a significant role in determining the pattern of one’s health seeking behavior in the future (Hodnett et al., 2007).
Upright positions and mobility may be more pleasant for laboring women and may have distinct advantages in promoting progress leading to a spontaneous vaginal birth. Mobility may be more pleasant for laboring women and their partners. Women need to be made aware of alternate positions and advantages and disadvantages in order for them to make an informed choice. Women are less likely to assume positions that are unfamiliar to them. Midwives and other obstetric health care personnel should be proactive in offering advice on alternative positions and resources to help women to be as comfortable as possible throughout labor. If women use birthing chairs, they should be encouraged to move about between contractions to reduce vulvae congestion and use an alternative aids such as a birthing char (De Jonge et al, 2008). Use of the lateral position for birth appears to protect the perineum and squatting using a birthing chair has been reported as a predisposing factor for third and fourth degree tears (Lawrence, 2009). The woman’s birth experience should focus on her individual needs and the experience she has should be facilitated by the midwife to ensure that she has choice and control over her position for labor and birth.
Significance to midwifery:
The practice of midwifery emphasizes safe, competent clinical management and advocates non intervention in normal processes (ACNM, 1997).
Every individual has the right to safe satisfying and health care with respect for human and cultural variations. The normal process of pregnancy and birth can be enhanced through education, health and supportive intervention (ACNM, 1997). The widespread use of the supine position during labor can be considered an intervention in the natural course of labor that, while appropriate in limited instances, is overused in current care for laboring women with detrimental effects to women, their labor process and their babies (Jonge 2004). The advice given by midwives is an important factor influencing the choice of birthing position. Midwives play an important role empowering women to adopt the positions that are most suitable for them at pivotal times during labor and providing ongoing support and advice throughout pregnancy and labor. Midwifery practice requires knowledge of research and an awareness of the need for critical analysis of personal practice. Midwives need to be aware of evidence- based practice related to maternal positioning in labor to promote normal birth for child bearing women. This inquiry will look at the factors that influence maternal positions in labor.
Chapter 2: Conceptual Framework & Review of Literature
Restatement of the problem
There is evidence from the literature that upright positions and being upright in the first stage of labor reduce the length of labor and do not appear to be associated with increased intervention or negative effects on the mother' and babies' well-being. Women should be encouraged to take up whatever position they find most comfortable during labor. The benefits of upright posture include a shorter second stage of labor, a small reduction in assisted deliveries, and a decreased episiotomy rate but an increased risk of severe blood loss. Birth position is influenced by many factors and the research investigating women's perceptions of comfortable positioning, and the extents to which women are influenced in relation to birth position are important contributions to the knowledge on the topic.
The purpose of this inquiry is to explore the factors that influence maternal positions in labor. Physical benefits that have been associated with the non supine positions are increased uterine pressure, more effective bearing down effects, improved fetal positioning, reduced risk of aorta caval compression and increased diameters of the pelvis, psychological benefits include reduced pain/backache, increased feeling of being in control and more effective communication with health professionals (Michel et al., 2002; De Jonge, 2004; Soong & Barnes, 2005; Stremler et al.,2005; Lawrence et al., 2009).
The majority of women in Western societies deliver in a supine position. It is claimed that the supine position enables the midwife/obstetrician to monitor the fetus better and thus to ensure a safe birth (Gupta, 2004). There is controversy around whether being upright or lying down has advantages for women delivering their babies. Several physiological advantages have been claimed for nonrecumbent or upright labor which includes: the effects of gravity, lessened risk of aorto-caval compression, stronger and more efficient uterine contractions, alteration in pelvic dimensions and reduction of back pain. The literature remains sparse with respect to the influence of co morbid medical conditions influencing position in labor.
Conceptual frameworks help guide a study to a conclusion by organizing the phenomena in an orderly coherent system. This involves integrating new research and existing knowledge through a review of prior research on a specific topic, then identifying or developing an appropriate framework. The overall purpose is to make the research findings more meaningful and generalizable, helping the reader understand the assumptions or conclusions and to identify possible biases the researcher may have that could influence the conclusion of the study. Research useful for clinical practice should provide evidence to support scientific approaches or strategies in caring for women (Polit et al., 2001).
The conceptual framework guiding this study includes kinesthesiology. This is the study of body position and movement.
The pelvis is comprised of two hip bones that are joined anteriorly via the symphysis pubis (3.5 cm long), and posteriorly they articulate with the sacrum (12 cm long) at the sacro-iliac joint. Each hip bone is composed of three bones that are joined together at the acetabulum; these bones are the pubis, ischium and Ilium. The female pelvis is tilted forwards relative to the spine. The angle of inclination is variable between different individuals and between different races; in adult Caucasian females, the pelvis is usually about 55° to the horizontal plane. Pelvic ‘tilt’, or inclination, is position-dependent and increases with growth into adulthood. The ‘true’ pelvis is bounded anteriorly by the symphysis pubis, the iliopectineal line laterally, and the sacrum posteriorly. It is composed of an inlet, a cavity and an outlet. The pelvic inlet of an adequately sized gynecoid pelvis is usually more than 12 cm antero-posteriorly, and 13.5 cm in the transverse diameter. The inlet is bounded anteriorly by the pubic crest, posteriorly by the promontory of the sacrum, and laterally by the ilio-pectineal line. The antero-posterior diameter of the pelvic inlet is also known as the true conjugate. However, clinically the most important diameter is the obstetric conjugate, which is the line between the promontory of the sacrum and the innermost part of the symphysis pubis – it is usually more than 10 cm. The line between the sacral promontory and the lowermost point of the symphysis is termed the diagonal conjugate. The mid cavity is spacious yet shallow, with both antero-posterior and transverse diameters usually approximately 12.5 cm. The birth canal narrows down inferiorly in the transverse section at the level of the ischial spines, but still measures more than 10 cm. In an ideal pelvis the ischial spines do not indent prominently into the pelvic cavity. The pelvic outlet is bounded by the inferior aspect of the pubic arch anteriorly, the tip of the coccyx posteriorly, and the ischial tuberosities and the surrounding ligaments laterally, with diameters of 12.5 cm antero-posteriorly and 11 cm transversely (Gabbe et al., 2007).
OBSTETRIC CONJUGATE & SAGITTAL OUTLET (Michel et al., 2002)
A conceptual map or diagram is a way to visualize a phenomenon, or the inter-relationship of theories present within a framework. Conceptual maps outline variables under investigation and the causal relationship between them. A schematic representation of a theory or conceptual model that graphically represents key concepts and linkages among them (Polit & Beck, 2008).For the purpose of this study, the following framework was used.
Factors influencing maternal positions in labor
According to Polit and Beck (2008), the reviewer must start with a question, formulate and implement a plan for gathering information, and analyze and interpret the information. A systematic literature review of articles dating from 1980 to 2009 was performed using Medline, CINAHL Pub med and Midirs. The searches for relevant research articles were further supplemented by evaluating the various bibliographies of relevant research papers as well as through references made in the body of the literature. This literature search included an international perspective. Key words that were used for the search included: maternal positions, labor first stage, second stage, mobility, birthing, parturition and pelvimetry. Approximately 32 suitable articles were retrieved and ten of these articles were reviewed, summarized and critiqued. Full text documents were obtained at the hospital medical library of Flagler Hospital, St Augustine, Florida.
The objective of Michel, et al. (2002) study was to measure the impact of supine and upright birthing positions on magnetic resonance imaging (MRI) pelvimetric dimensions. The study population comprised of thirty-five non pregnant female volunteers, aged 22-43 years old. Each volunteer provided informed written consent following full explanation of the examination procedure. The study protocol received approval from the institutional review board. Eligibility criteria were used to establish population characteristics and used to maximize the validity of the population construct (Polit & Beck, 2008). The women were recruited in to two groups which included a nulliparous group and a parous group. Nine parous women had one child; one had two children. All had delivered vaginally at least 9 months before inclusion.
Imaging Technique: A 0.5-T low field vertically open configuration magnet system was used with the body flex surface coil. Imaging was performed with patients in the supine, hand knee, and squatting positions (See diagram 1 & 2).A special wooden construction allowed women to maintain the upright position in the scanner. To avoid displacement, the body flex coil was used. A T1- weighted fast spoiled gradient- echo sequence was performed with the patient in the mid sagittal, axial, and oblique, which was defined in the study as the plane of sacral promontory to the top of the symphysis, planes. The total individual study time was less than 60 minutes in all cases. Image Analysis: The obstetric conjugate; sagittal outlet; and interspinous, intertuberous, and transverse diameters were measured on MR console using the same radiology technician. The obstetric conjugate and the sagittal outlet were both assessed in the mid sagittal plane. The interspinous and intertuberous diameters were assessed in the axial plane. The study provides photographs of these positions. Continuous variables were presented as means and standard deviations. Absolute pelvic measurements in the three positions and the differences between them were compared using Wilcoxon's signed rank test with Bonferroni's adjustment. The data were tested for correlation with body weight, body mass index, and age using Spearman's rank correlation coefficient and for differences between the nulliparous and parous groups using the Mann-Whitney test. A p value of less than 0.05 was considered statistically significant. Statistical analysis was performed using Stat view 5.0.1 software.
Results: MR pelvimetry in the three positions was feasible in all subjects although the hand to knee and squatting positions were difficult to maintain. Individual study time and positioning took less than 60 minutes. Diagnostic quality images were obtained in every volunteer and samples of these images and dimensions were provided in the article.
Patients in the hand to knee and squatting position, the sagittal outlet (11.8 +/- 1.3 cm; p=0.002 and p=0.01, respectively); Interspinous diameter (11.6+/- 1.1 cm and 11.7 +/- 1.0 cm vs. 11.0 +/- 0.7 cm; p< 0.0001, in both cases). Intertuberous diameter was wider with patients in the squatting position than in the supine position (12.7+/- 0.8 cm vs. 12.4 +/- 1.1 cm; p= 0.01). Transverse diameter did not change significantly in any position (See Table 3).
TABLE 3. Pelvic Measurement for 35 Women in Supine, Hand-to-Knee, and Squatting Positions (Michel et al., 2002)
Mean ± SD (cm)
Mean ± SD (cm)
Mean ± SD (cm)
12.4 ± 0.9
12.4 ± 0.8
12.3 ± 0.8
11.5 ± 1.3
11.8 ± 1.3
11.7 ± 1.3
11.0 ± 0.7
11.6 ± 1.1
11.7 ± 1.0
12.4 ± 1.1
12.5 ± 0.8
12.7 ± 0.8
12.9 ± 0.7
12.8 ± 0.7
12.8 ± 0.8
Diagram 1. Hand to knee position (Michel et al., 2002)
Diagram 2 Squatting position (Michel et al., 2002).
Authors conclusions. The sagittal outlet and interspinous diameter were significantly greater in the hand to knee position and squatting positions than in the supine position, as was the intertuberous diameter in the squatting position. The obstetric conjugate was the only dimension to be significantly smaller in the upright squatting position than in the supine position. The obstetric conjugate of the pelvic inlet is the distance from the sacral promontory to the superior aspect of the symphysis pubis and usually measures 10-11 cm, midcavity is the measurement between the ischial spines, usually the smallest diameter of the pelvis and should be greater than 10 cm. The pelvic outlet the anteroposterior diameter from the coccyx to the symphysis pubis usually 13 cm and the transverse diameter between the ischial tuberosities around 8 cm (Gabbe, 2002). The study's data confirms those published by Russell, (1969) who found a significant increase in interspinous diameter in the last trimester of pregnancy and after childbirth on changing from supine to the sitting position although further research by Gupta, (1994) found no significant change in inlet and outlet dimensions between patients in the sitting and squatting positions using lateral radiographic pelvimetry. The authors attribute this to the limited size of their study population. Differences in posture can significantly increase female pelvic dimensions and provides objective confirmation of the advantages of changing birthing position to facilitate vaginal birth.
The weakness identified in the study was that no pregnant women were included in the study; this limitation is recognized by the authors. Prevention of measuring the influence of pregnancy related joint laxity in late gestation can be considered a limitation; also considering changes in pelvic dimensions become more pronounced in pregnancy. Ethical considerations of scanning stress for pregnant women in the squatting and hands and knees position in an exhausting position to hold and image quality was recognized as a limitation within the study. See diagram 1 & 2 for hand to knee position and squatting position.
The author's research purpose is stated unambiguously in the study and is easy to identify, the implications of female pelvic outlet dimensions have a profound significance for midwifery practice and the choice women make regarding positions used for delivery. The research design was appropriate; as mentioned by Polit and Beck (2008) the research design incorporates some of the most important methodologic decisions researchers make. Although the sample size was small, the measurements changes were being compared from the same subject each time thereby reducing the need for a large number, which according to Polit and Beck (2008) is appropriate for this study type. The study was subject to external review, informed consent was obtained and designed to minimize risks of the participants. The importance of informed consent means that participants have adequate information regarding the research, are capable of comprehending the information, have the power of free choice enabling the participant to consent or decline voluntarily (Polit & Beck, 2008).The findings of the study show that changes in birthing position augment pelvic dimensions and therefore can be obstetrically advantageous in factors influencing maternal positions in labor.
Chen et al. (1987) carried out a study to determine which components of uterine activity are affected by different positions of labor. The study took place at the Department of Obstetrics and Gynecology, Oita Medical College, Japan. During September 1983 and April 1985,183 patients who had taken prenatal classes, had full term spontaneous labors and a single fetus in cephalic presentation were enrolled in the study. Sixty seven patients were excluded from the study for reasons as follows: oxytocin augmentation, cesarean section and request for epidural analgesia leaving 116 participants for inclusion in to the study. There is no mention of ethical approval or consent having been obtained. The women were assigned following the order of admission to one of three groups: 1) Sitting for the entire labor, first on a sofa and then in a birthing chair, with a back elevation of 65 degrees; 2) Supine in first stage and sitting in the birthing chair for 2nd stage; and 3) Supine for the entire labor, dorsal or lateral in bed with a pillow in first stage and lithotomy in second. Amniotomy was performed at 3-4cm and the fetal heart rate was monitored by an electrode on the fetal scalp and the intrauterine pressure monitored by insertion of an open tip catheter in to the amniotic cavity. To allow full mobility during the first stage, direct monitoring was transmitted via a telemetry system (model 315; Corometrics Co.) In second stage, women were told to bear down only with an involuntary urge. No analgesia or anesthesia except local was used. The mean resting uterine pressure was greater for both nullips and multips when sitting; however, no difference was observed between sitting and supine position during contractions. See table 4 for the pressure values and p values.
For nullips, there was no significant difference between the two positions in length of time from 5-10cm, but the second stage was significantly shorter for those sitting. For multips, the first stage was significantly shorter for women who were sitting, but there was no difference in length of second stage.
Table 4: Modified Montevideo units of uterine contractions (Chen et al., 1987) mm/Hg per uterine contractions (Chen et al., 1987)
There were no significant differences in fetal heart tracings or umbilical cord pH between groups.
The results of the study indicate that the elevated resting pressure helps enhance the expulsive force rather than uterine contractility. The non-supine position results in stronger bearing down efforts which are important in the progress of labor in the second stage. Maternal position does not affect uterine contractility, the increased resting pressure in the sitting position is of some importance in supplementing the downward delivery force and increased bearing down in the sitting position could help to significantly shorten the duration of the third stage.
Chen's study showed a weakness regarding allocation concealment and ethical approval agreement was not mentioned in the article. Not having formal ethics approval opens the study to criticism with respect to participant protection, participant equitability, participant confidentiality and welfare (Polit & Beck, 2008).Following randomization there was a high number of women who failed to meet on going criteria and therefore dropped out of the study out which can lead to bias. Both of these studies help to define objectively the enhancement in pelvic outlet and the enhancement in uterine work both of which result in shorter duration of the second stage of labor. This information is useful in the education of both providers and patients.
Ank De Jonge (2008) conducted a qualitative study to ascertain how independent midwives in the Netherlands reach decisions on which positions to use for women in the second stage of labor.
The method: Six focus groups (4-6 midwives in each group), with a purposive sample of 31 midwives, were conducted in 2006-2007 in the Netherlands. Interviews were conducted either in the midwives’ homes or midwifery practices and lasted between 1-1.5 hrs. Prior to each interview, a questionnaire was sent to participants to collect data on individual and practice demographics. Midwife researchers conducted most of the focus groups, assuming roles as moderator and assistant. In one research group a research psychologist was the assistant. Notes were taken and non verbal communication observed. The data was interpreted using Thachuk's models of informed consent and informed choice.
Thachuk distinguishes the medical model of informed consent as one that is based on the right to relevant information and competent and non-coerced consent. The woman is a passive recipient of the information and choices the professional decides to give. In the midwifery model of informed choice, the locus of power is shifted to the woman as the primary decision maker. The relational aspect of autonomy is emphasized, and both the midwife and the woman actively participate in the process of informed choice (Thachuk, 2007). All interviews were transcribed and a software program was used to aid the analysis.
Findings: Thachuk’s models helped distinguish between two different approaches of midwives to women's positions during labor. When giving informed consent, midwives explicitly ask a woman's consent for what they themselves prefer. When offering informed choice, a woman's preference is the starting point, but midwives will suggest other options if this is in the woman's interest. Obstetric factors and midwives working conditions are reasons to deviate from women's preferences (Jonge, 2008). In order for midwives to give women informed choice regarding birthing positions, information needs to be given throughout the ante partum period and women's preferences discussed. Women should be prepared for the unpredictability of feelings during the reality of labor and obstetric factors that develop that may interfere with choices. Equipment for non-supine births should be midwife-friendly such as birthing balls and wall bars and midwives and students should be able to gain experience in assisting with non-supine positions.
The strengths of the study: The research question is congruent with a qualitative approach. An appropriate design was used within the study; a focus group study of independent midwives who work autonomously in their practice, this generates more ideas through the exchange of different approaches to dealing with birthing positions. Participants were encouraged to express their views openly. There is limited research in to the views of midwives on birthing positions and the findings in the study heightened the need for further research in to this area.
The weakness of the study: Some of the midwives knew the interviewers which according to (Polit & Beck, 2006) could be construed as bias. Knowledge of the group facilitator may lead the participant, so therefore some threat of potential biases exists between midwives and participants. No distinction is given within the study between the second stage position and delivery position which is significant to the findings. A definition needs to be addressed between these two areas. The study provides valuable insight and information regarding the influence of midwives and maternal position choice in labor and highlights the fact that there is limited research in to midwives views of birthing positions and the difficulty of offering choice to women when certain societies are heavily biased towards the use of the supine position. Women need evidence based information on the advantages and disadvantages of alternate birthing positions in order to make informed choices. The distinction between informed consent and informed choice plays a relevant role in this research. The limitation of the midwives experience in non-supine positions favors a greater bias towards practitioner preference influencing the final position assumed for the delivery. This would suggest benefit in training practitioners in the methods of non-supine deliveries. This study helps to define where we are at present with respect to practitioner preference for the maternal position at the time of delivery. With this information, future studies and training can be designed to more adequately educate and counsel the providers as well as the patients with respect to their options for positions in labor and delivery.
Al-Mufti, Morey, Shennan, & Morgan (1997) conducted a quantitative, prospective study to determine the effect of patient controlled combined spinal epidural analgesia on maternal pulse and blood pressure and fetal heart rate in primigravid women, when adopting different positions in labor. Prospective studies, according to Polit and Beck (2008), are considerably stronger than retrospective studies, although not as powerful as prospective studies that involve a prior hypotheses and the comparison of cohorts known to differ on a presumed cause (Polit and Beck, 2008).A total of 55 primigravid women were included prospectively in the study which was carried out at a teaching hospital in London, England. Ethical approval was obtained; procedures need to be developed to ensure the study adheres to ethical principles (Polit & Beck, 2008).
Recruitment for this study occurred after successful placement of a combined spinal-epidural analgesia placed at the request of primips at term (37 completed weeks or more) and once screening for appropriateness of mobilization had been made. This screening was performed by the anesthetist 20 min after placement of the analgesics. A record was made of the level of the sensory block, presence of sympathetic block and the ability of the woman to raise her legs straight off the bed against resistance.
Forty women had supervised standing top up's (re-dosing of epidural analgesia) given by an anesthetist. A further 15 women had patient controlled epidural analgesia (PCEA) top up's given in each of the standing, sitting and lying positions. Systolic, diastolic and mean arterial blood pressure and pulse rate were measured using a pregnancy validated automatic ambulatory blood pressure monitor and recordings of changes in BP noted for the first half an hour following top up. Fetal cardiotocography (CTG) was recorded for 30 minutes, using Hewlett Packard 80240A CTG Telemetry monitor, before and after epidural top up. The first 40 women studied following insertion of spinal injection, were asked to lie on their side for half an hour and then asked to stand and a top up of 10ml of fentanyl and 0.1% bupivacaine were injected, by the anesthetist. BP and pulse rate were recorded on two occasions prior to analgesia and while each woman was standing. Women were asked to stand for half an hour while measurements of BP and pulse rate were recorded every 6 minutes. In the second part of the study, 15 women with PCEA top ups were asked to adopt three positions: left lateral position, sitting and ambulating for at least half an hour after giving their own top ups. Each woman with PCEA was asked to adopt each of the three different positions at least once at random; this allowed assessment of the changes in BP and pulse rates as well as CTG changes when top ups were given in these three positions of subjects whose scores on a dependent variable are used to evaluate. Polit and Beck (2008) refer to this as a comparison group, a group of subjects whose scores on a dependent variable are used to evaluate the outcomes of the group of primary interest. Fetal heart rate decelerations were classified by two experienced independent obstetricians, blinded both to the time of top up and the position the woman was in when receiving the top up, this was recorded using FIGO classifications (International Federation of Gynecology and Obstetrics). Normal distributions of BP and pulse rate data were confirmed by plotting values against their normal scores. Statistical analysis was carried out using paired t test. Fisher Exact test was used to compare proportions of women with CTG changes in the different positions that the women adopted. A clinically significant fall in BP was considered to be a fall in systolic BP < 100mg Hg. Ethical approval was obtained to use ambulatory BP monitoring on all participants.
Results: In the first 40 women, there was no clinically significant fall in blood pressure (<5mm Hg).The subsequent 15 women who had PCEA top ups had no fall in blood pressure in the standing and sitting positions, though the average BP fell significantly when a top up was given in the lying position. Maternal heart rate increased significantly at 12 minutes post top up when the women were in the standing position (p=0.0018). BP and pulse recordings pre top up were BP 127/ 79, pulse 85; after 6 minutes BP 126/78, pulse 90 after 12 minutes BP 123/77, pulse 94 and after 30 minutes BP 123/75, pulse 86 In the 15 women who had PCEA top ups, the CTG monitoring showed improvement in decelerations when women were in the standing position but deterioration when in the lying position (p<0.01).Five out of forty women had decelerations present from the top up and in three of these the decelerations improved after top up. Following standing top up in 10/15 women the decelerations improved (disappeared or decreased in frequency) and none had deteriorated. On sitting, six cases improved and one deteriorated. In the lying position, only two improved and seven actually deteriorated. Significantly more women therefore had improved decelerations when top ups were given standing as compared with lying (P<0.01).
The weakness in this study included the small number of participants. Fifty-five women were recruited of which only five women had top up's in the lying position. The smaller sample size tends to produce less accurate estimates than larger ones (Polit & Beck, 2008).Another weakness identified was the lack of stringent inclusion criteria. CTG monitoring has been shown to have a wide range of interpretation although the authors made an attempt to address this by having two independent obstetricians classify the strips according to FIGO classification and having them blinded to the arms the participants were in. There is no mention as to the level of concordance between the two experts reviewing the CTG monitoring. The strengths included that a prospective design was used, and the study was performed in a single institution which allows for consistency, although having multiple sites is advantageous in terms of enhancing the generalizability of the study findings. (Polit & Beck, 2008). The BP and pulse observations were obtained by validated automated equipment which reduces chance of error (Polit &Beck, 2008).
In summary, a combination of spinal and epidural analgesia with low dose bupivacaine and fentanyl maintains motor function and allows women to walk about during labor and may cause less hypotension than when a woman is lying down. This would be more conducive to maintaining maternal choice of positioning. Reduced hypotension post epidural placement would also reduce the added stress experienced by the patient and family as a result of the fetal heart monitoring changes. This study with its objective assessment of blood pressure changes and fetal heart tone changes is useful in guiding future studies in exploring the utility of mobile epidurals which in itself would serve to reduce significantly the one of the barriers to non-supine positions in labor in that the women who choose epidural anesthesia would be able to support themselves in these positions.
Soong & Barnes (2004) conducted a quantitative study to examine the association between maternal position at birth and perineal outcome in women who had a midwife attended spontaneous vaginal birth and an uncomplicated pregnancy at term. Methods: Data from 3,756 births in a major public tertiary teaching hospital were eligible for analysis. The larger the sample size, the more representative of the population it is likely to be (Polit & Beck, 2008). The necessity for sutures in perineal trauma was evaluated and compared for each of the following: maternal age, first vaginal delivery, induction of labor, not occipitoposterior, use of regional anesthesia, deflexed head and newborn birth weight> 3,500g. Birth positions were compared against each other. Study variables included age, parity, maternal position at time of birth, accoucheur, flexion of the head, analgesia use, previous perineal trauma, need for suture of the trauma, birth weight, type and degree of perineal trauma and estimated blood loss. The attending midwife encouraged women to give birth in positions with which they felt most comfortable using. Subgroup analysis determined whether birth positions mattered more or less in each of the major factors studied. Statistical analyses were performed using Statistical Package for Social Science software. The chi square test was used to compare categorical variables, and p values of < 0.05 were considered statistically significant; odd ratios and 95% confidence intervals were calculated.
Results: Most women , 65.9% gave birth in the semi recumbent position, 14.6 % in the lateral position, 1.3% supine, 0.7% lithotomy, 1.4 % kneeling , 9.9% all fours, 1.3 % squatting, 0.8%, 4.1% standing. Of the 3,756 women, 1,679 women, (44.5%) required perineal suturing; semi recumbent position, defined as forty five degrees, was associated with the need for perineal sutures, whereas all fours was associated with reduced need for sutures. When regional anesthesia was used, semi recumbent position was associated with a need for suturing, and lateral position associated with a reduced need for suturing.
The weaknesses of the study, which were identified by the authors, included: unequal groups, birth positions were not randomly assigned and therefore an association between birth positions and alternate obstetric factors that may affect perineal status. Lack of statistical significance in other birth positions cannot be taken as evidence of no difference because the numbers may be too few in certain groups. Strength of the study included a large sample size of eligible women over a three year period. Having a study sample of this size over a three year time period allows for more information to be gathered making the research more descriptive, with improved accuracy and reliability of the results (Polit & Beck, 2008). The author concluded that women should be given the choice to give birth in whatever position they find comfortable. Maternity practitioners have a responsibility to educate women regarding birth position and potential effects on perineal trauma. This study was large though lacked prospective randomization. Specific classification of perineal trauma was not given. A grade three laceration or more has greater consequence on sphincter performance. This information would lend more weight to deciding on which position is best assumed. This study suggests some benefit could be made from delivering in the all fours or left lateral position with respect to reducing need for perineal suturing. This information would be useful in counseling practitioners as well as patients on drawbacks with delivering in the semi-recumbent position versus the all fours and the left lateral.
Adachi, Shimada and Usui (2003) provided quantitative research to determine if maternal position reduced the intensity of pain during cervical dilatation from 6-8 centimeters. The study was carried out in Tokyo, Japan on 30 primiparous and 19 multiparous women (N = 58) who alternately assumed the sitting and supine positions for 15 minutes during cervical dilatation from 6-8 centimeters. Labor pain was measured by the visual analog scale (VAS), which has a horizontal line marked in millimeters from 0 to 100 with two opposing extremes at each end (i.e., no pain and worst possible pain) A score was determined by measuring the distance from the no pain end to location marked.
Method: Eligibility criteria included: women 37-42 weeks gestation, 6-8 centimeters dilated, no obstetric risk factors, single fetus in cephalic presentation, no use of pharmacologic pain relief, uterine contractions occurring at intervals of 5 minutes or less, Japanese as the native language. Exclusion criteria included: an accelerated progress of labor during the intervention, inducement of labor, preference of particular position. Informal written consent was obtained from each participant. Pain intensity was measured using the visual analogue scale (VAS), which has a horizontal line marked in millimeters from 0 to 100 with two opposing extremes at each end; no pain and worst possible pain. VAS has been used in various clinical trials to measure pain and is reported to be reliable as a pain measuring instrument (Lundeberg, 2001).Participants marked the line representing the perceived intensity of labor pain with two opposing extremes at each end no pain and worst possible pain.
Design: A randomized and cross over study in which the same group of subjects served as both the control and experimental group was used to control the influence of these factors (Polit and Beck, 2008). Participants were randomly assigned to one of two groups in which either the supine or sitting position was first used and then alternated with the other position to avoid order effect. Analyses were performed using SPSS for windows, Advanced Statistics Release 9.0J. Unpaired t-test and Fisher's exact-test methods were used to compare the back ground variables. According to Polit and Beck (2008), these methods are appropriate for small sample sizes (Polit & Beck, 2008).
Results: The pain scores for the sitting position were significantly lower than those of the supine position. See table 5 below. The Wilcoxon signed-ranks test showed the VAS scores the total labor pain which was defined as both abdominal and lumbar pain, during contraction values (p=.011), continuous total labor pain (p= .001), lumbar pain during contraction (p < .001) in the sitting position which was significantly lower than in the supine position. The diminished pain scores were greater than 13 millimeters, which is the minimum clinically significant change in patient pain severity as measured with the 100 millimeter VAS. The largest decrease occurred in lower back pain. No significant differences were found for abdominal pain scores in either the sitting or supine positions.
The strength of the study includes the design that was used, using a randomized method for allocation in to two groups and the strict screening criteria to meet eligibility. If subjects are placed in groups randomly, there should be no systematic bias in the groups with respect to attributes that could affect the dependent variable (Polit & Beck, 2008).Adequate power was pre determined using the two tailed t test with a significance level of 0.05. Based on this, the minimum sample size for this cross over design was 43 and this was exceeded by the final recruitment number of 58. Screening criteria and the randomization allows for the two groups to be similar, making the results more valid (Polit & Beck, 2008).The sample size of the study was small but should not interfere with the efficacy of the study between pain intensity measurements. The statistical data analysis was appropriate, the authors made efforts to examine the comparability with regards to abdominal pain and lumbar pain. (Polit & Beck, 2008). The instrument used to assess labor pain, VAS, has been reported to be a reliable measuring instrument Jackson, 2001; Gallagher, 2001 .This study highlights the importance of maternal position especially when lumbar pain appears to be the most distressing component. This study being well designed with randomization and prospective in nature with the use of validated tools for assessment of variables makes a solid argument for laboring in the late first and early second stage in the non-supine/sitting position. This information further endorses to practitioners and patient the benefits of maintaining mobility and avoiding confinement to the bed during labor.
Perineal trauma and Back Pain
De Jong, Johanson, Baxen, Adrians, Van der Westhuisen & Jones (1997) designed a randomized controlled trial to assess the maternal and neonatal effects of upright compared with recumbent positions during delivery, in terms of defined outcome variables. The study was conducted at a midwife based maternity unit in Cape Town South Africa. Women were assessed for eligibility; 517 women were included all having singleton pregnancies with a cephalic presentation, at >34 weeks of gestation with no risk factors present. Randomization envelopes were prepared from a single computer generated number sequence and late in the first stage of labor women were randomized by the use of sealed opaque consecutively numbered envelopes, and participants were allocated to either the squatting in the second stage group or the routine management group. At the end of the study, all the envelopes were accounted for. Until the beginning of the second stage of labor management of the two groups were identical with women being encouraged to mobilize, sit or recline. In both groups fetal monitoring was performed according to the standard practice of intermittent auscultation, with cardiotocograph tracing if abnormalities were heard. The routine management of labor was unchanged .The routine management of labor and CTG monitoring was not defined in the study which can be seen as a weakness. Analgesia was given by means of pethidine or hydroxyzine as required. The second stage of labor and delivery was accomplished with the woman in the supine position on a delivery bed supported by a partner. The upright second stage management involved a squatting posture on a stool covered with a foam mattress, with helpers supporting her on both sides. All details of the delivery were recorded and the woman's subjective assessment of the delivery was recorded the following afternoon by an independent midwife blinded to the mode of delivery. The principal outcomes of the study were the proportion of women with a hemoglobin of <11 g/dl on the second day after delivery, and second or third degree injuries of the perineum.
Power of the study and methods of analysis: The baseline incidence of low Hb levels in the study was approx 35% and the baseline incidence of second or third degree injuries about 5%. A study with 250 women in each arm would have a power of 90% (p=0.05) detecting a difference in the proportion of low hemoglobin levels, if this level were increased by 45% , or of only 75% of detecting a doubling of the proportion of perineal injuries by 10% by adoption of the upright position. Power analysis can be used to reduce the risk of a false positive by estimating in advance how big a sample is needed (Polit & Beck, 2008). The Mann Whitney U test was used to test differences of non-normally distributed continuous variables, with X square test being used to analyze frequency variables, the results were reported as odds ratios (95% confidence interval).Meta- analysis of the results of this paper combined with previous studies was carried out using Review Manager. The study protocol was approved by the University of Cape Town Ethics Committee. Results: Of the 517 women in the trial, 257 were allocated to the upright group for delivery and 260 were assigned to the recumbent group. Thirteen women in the upright group and 12 in the recumbent group required transfer before delivery for instrumental deliveries, low hemoglobin, one with eclampsia. Women who adopted the upright posture for delivery experienced less pain, pain assessment was recorded the following afternoon by an independent midwife using the Trent test X squared (validated pain score) (1 df) = 7.98, exact P= 0.0034., Women in the upright posture also experienced less perineal trauma and fewer episiotomies also experienced less pain than those who delivered in the supine position. There were no significant differences in length of labor, or amount of blood loss, although there were significantly fewer episiotomies in the upright position. There were no differences between groups in terms of the total number of women with perineal trauma requiring suturing. There were no significant differences between the outcome of the fetus and newborn infant in the groups. Fewer women in the upright group had significant pain during delivery.
The authors of this study show that an upright birthing position will not adversely affect labor outcome for women but may be beneficial as significantly fewer women experience discomfort in the second stage and a reduction in the number of third degree tears. Data, regarding EBL suggests an increase in the rate of post partum hemorrhage; this however is not supported by objective evidence of postnatal hemoglobin measurements and rates of blood transfusions. For women of low obstetrical risk, choice of posture during delivery should be encouraged. Weaknesses that were identified included: no validated pain scale tool was used; estimated blood loss was assessed by visual assessment. Objective laboratory measurements are advised to examine the difference in blood loss (Polit & Beck, 2008). There is no mention as to how the third stage was managed with respect to whether a physiologic or active. The unclear parameters and measurements by the authors and their failure to define labor protocols and routine CTG monitoring compromises the validity of their conclusions and reproducibility (Polit & Beck, 2008).The strength of the study was that it was a prospective study, adequately powered in a single institution. The use of randomized envelopes, prepared from a single computer-generated number sequence, and sealed using opaque envelopes enhanced the credibility of the study. This study though weakened by some design flaws does provide evidence to support the safety of non-supine labor and delivery especially in the areas of pain and perineal trauma. This information could used to design future studies and encourage better practitioner education in the area of non-supine labor.
Stremler, Hodnett, Petryshen, Stevens, Weston, Willan (2005) conducted a quantitative randomized trial on one hundred and forty seven pregnant women to evaluate the effect of maternal hands and knees positioning on fetal head rotation from occipitoposterior to occipitoanterior position, persistent back pain and other perinatal outcomes. Methods: Thirteen labor units in university affiliated hospitals participated in this multicenter randomized controlled trial, for a 28 month period in 2000-2002 in Argentina, Australia, Canada, England, Israel and the United States. According to Polit & Beck, multi-site sampling allows the results to be more generalizable. Research ethics board approval was obtained for all participating centers. Study participants included 147 women laboring with a fetus at > 37 weeks gestation and confirmed by ultra sound to be in the occipitoposterior position. Seventy women were randomized to the intervention group which included maintenance of the hands and knees position for at least 30 minutes over a one hour period during labor and 77 to the control group, no hands and knees position. The primary outcome was fetal rotation and the secondary outcome was level of back pain and women's views with respect to positioning.
Eligible women were recruited based on the occurrence of one or more of the following criteria presumed to indicate labor with a malpositioned fetus: persistent back pain, slower than normal progress, vaginal examination, recent ultrasound, Leopold's maneuvers or abdominal contours suggesting occipitoposterior position, irregular contraction pattern, urge to push before full dilatation, suprapubic pain, fetal heart rate located at the maternal flank or edematous cervix. Eligible women were required to be in hospital in early or active labor with a singleton pregnancy in cephalic presentation at > 37 weeks gestation, occipitoposterior position of the fetal head confirmed by ultrasound examination. Women were excluded if second stage of labor was expected within one hour, complications of pregnancy or any other contraindications to assuming a hands and knees position such as an immobilizing epidural. Following informed consent an ultra sound confirming occipitoposterior position was performed and if confirmed, the laboring woman was asked to complete the Short Form Mc Gill Questionnaire and then randomized. The randomization process involved prognostic stratification for parity and anesthesia use, incorporated random block sizes of 4-6 which was controlled with the use of a telephone- based, computerized randomization system. Group allocation remained unknown to clinicians and research assistants collecting the data. Women assigned to the intervention group were asked to maintain the hands and knees position for as much time as possible over a period of 60 minutes, for a minimum of 30 minutes in total the information was recorded on trial data forms by the midwife, nurse or labor partner. Women assigned to the control group were able to use any position except the hands and knees position. Participants were asked to complete a questionnaire before discharge to verify compliance with the assigned group and determine maternal evaluations of positions used. The questionnaire contained the Labor Agentry Scale, a unifactorial, 10 item, Likert-type rating scale used in many studies of women's experiences of personal control during labor and birth. Cronbach’s alpha reliability coefficient for the Labor Agentry Scale has consistently been shown to be > 0.88. (Stremler et al., 2005). Data was scanned directly in to the study data base using TELEform software and statistically analyzed using SAS version 8.2. Demographic, maternal satisfaction. A two sided significance level of 0.005 (two sided) was used for other comparisons, to account for multiple comparisons and preference variables were analyzed and compared using descriptive statistics.
Results: Women randomized to the intervention hands and knees group had significant reductions in persistent back pain. Eleven women (16%) allocated to use hands and knees positioning had fetal heads in occipitoanterior position following the 1 hour study period compared with 5 (7%) in the control group (p value 0.18).Trends toward benefit for the intervention group were seen for several other outcomes, including operative delivery. Maternal hands and knees positioning during labor with a fetus in the occipitoposterior position enhances fetal rotation, reduces persistent back pain and is acceptable to laboring women. The strengths of this study included a well designed prospective randomized trial. Inclusion criteria were clear and objectively determined. Outcome measures were clear and determined by using validated tools, VAS and SF-MPH. The weakness identified was that the study was underpowered - 364 predicted participants needed and 147 were obtained. This meant that statistical significance was unlikely to be demonstrated. This study further reinforces previous findings on the benefits of all fours with respect to back pain reduction in labor.
This well designed study, although under-powered, with multinational input is useful in guiding future research in answering the question of whether the all fours position is especially useful in women laboring with an occipitoposterior position in order to reduce the risk of instrumental or operative delivery.
De Jonge & Largo-Janssen (2004) conducted a qualitative study to gain insight into the influences on women's use of birthing positions, and in to the labor experiences of women in relation to the birthing positions they used. The study took place in the Netherlands from April to December 2002. A pilot cohort study was conducted in to the advantages and disadvantages of the supine position versus other positions during the second stage of labor. A purposive sampling methodology was used. The inclusion criteria included: women who commenced the second stage of labor under midwifery care. Written consent was obtained and medical data regarding delivery was collected and a registration form completed with questions relating to birthing positions. A survey questionnaire was sent to the women for completion approximately 6 weeks following delivery to provide quantitative information about their experiences and health problems. Although this approach is cost effective for reaching geographically dispersed respondents it tends to yield low response rates. Individual interviews were held to collect in depth, personal data. Women were questioned about positions used both the first and second stage. Choice of where the interview took place was given to the woman i.e., home, health facility etc and written consent obtained at the commencement of interviews. Complete anonymity was used; two researchers have access to the original interviews. The interviewer was also one of the midwives who provided care for the woman and assisted in five of the deliveries. All interviews were recorded, transcribed and analyzed by the interviewer. Background information from the pilot was used; free text, filled in by the midwives on the registration forms and by the women on the questionnaires which was used in the analysis. This triangulation of methods which is research designed to develop or refine methods of obtaining, organizing, or analyzing data (Polit & Beck, 2008), was thought to enhance the quality of findings. Coding categories were used to analyze data and themes were formulated and discussed by the second researcher.
Results: Advice given by the midwife was the most important factor that influenced the choice of birthing position. Other influences on the use of birthing positions included information women obtained from midwives during antenatal classes, information via the media and other women's stories. The strength of this study was that women were given a choice of where interviews took place, by one researcher using a triangulation method. The strengths of interviews outweigh those of questionnaires because of the depth of questioning involved (Polit & Beck, 2008).
The design of this study lacked use of validated questionnaires, research was conducted by a midwife who also performed 25% of the deliveries, and questionnaires were sent six weeks following delivery which makes it difficult for women to recollect information. The study was small. No mention is given to the response rate of the questionnaire.
Authors conclusions. The author concluded that the experience of type and intensity of pain and accompanying preference for a certain birthing position varied widely. Women were most familiar with the supine position. This was due to the dominance of this position in the westernized societies. Women wanted practical information from midwives regarding various positions during the ante partum and intrapartum period. Choice of birthing positions was influenced more by the midwife than by the women's personal preference. Future research needs to examine factors that would enable midwives and other obstetric health professionals to empower women to have informed choice. This study is valuable in that there is very limited data published exploring women's views on their perspective of delivery position through an in depth interview in a non threatening environment. This study helps to highlight the need for further research perhaps with validated questionnaires on assessing maternal preferences in different cultures.
Olson & Cox, (1990) conducted a study to evaluate the relationship between maternal birthing position and perineal outcome. The study was a retrospective descriptive analysis of the perineal outcome of 335 patients who gave birth vaginally between December 1980 and December 1988.Women attended childbirth education classes as part of their prenatal care and during these classes, birthing positions and perineal injury were topics of discussion, which included a film illustrating different birthing positions. Selection criteria involved low risk obstetric women, with a mean age of 24.5 years, generally healthy, living in a rural family physician group practice located in a community in northwestern Wisconsin. The study examined the outcome of 335 patients who gave birth vaginally, women whose babies were delivered by cesarean section (n=102, 21.9%), and those that gave birth in other facilities including at home (n=29, 6.2%).
Data was collected from labor and delivery summaries completed by the obstetric nurses and birth reports completed by the obstetric nurses and birth reports completed by the physicians. These reports included data on maternal birthing position, perineal outcome, complications during delivery such as shoulder dystocia, and reasons for episiotomy if performed. Perineal outcome was recorded as one of four mutually exclusive outcomes: intact perineum, second degree laceration needing repair, episiotomy and third degree perineal injury and episiotomy extension. Parity was treated as a dichotomous nominal variable, and analyses were conducted on primiparous and multiparous women. Maternal position was treated as a nominal variable. Birthing positions were defined as lithotomy or dorsal recumbent on a delivery bed, sitting position in the birthing chair, with a few women assuming a lateral or side lying position while using the birthing bed. See table 6 defining birthing positions.
Data was analyzed by primiparous or multiparous status, birthing position and perineal outcome. Chi square tests of independence were used to examine the association among factors, and a p value < .05 was considered statistically significant. Excluded from the analysis were women whose babies were delivered by cesarean section and those giving birth in other facilities including home. Of the 335 women who gave birth vaginally, 113 were primiparous and 222 were multiparous. Sixty six percent of the women whose babies delivered vaginally attended a series of childbirth education classes as part of their prenatal care. The most common birthing position used by women in the study was the semi sitting or Fowler's position in the birthing bed (43.6%; n= 146). Ninety-four women (28%) gave birth on the delivery table from the lithotomy or recumbent position with legs in stirrups. Eighty women (23.9%) used the birthing chair and gave birth while in a sitting position. The lateral or sitting lying position on the birthing bed was assumed by 15 women (4.5%). Multiparous women used the semi sitting position in the birthing bed more frequently than primiparous women The use of a particular for delivery varied with parity (X 2= 8.009, df =3, p<.05). Primiparous women were more likely to use the lateral, sitting or lithotomy positions on the bed, chair and table.
TABLE 6: Definition of birthing positions
|Supine Position||Patient on her back with knees slightly bent|
|Kneeling/ hands and knees||Patients weight chiefly on her knees, possibly also on her|
|arms, hands, or upper chest. Torso bent at hips|
|Sitting||Patient's weight supported by her buttocks and thighs; knees bent; feet flat on bed or floor|
|Squatting||Patient's weight rests on her feet; knees bent|
|Lithotomy||Patient lies on her back with hips and knees flexed and thighs abducted and externally rotated|
|Lateral||Patient lies on her left or right side|
|Recumbent|| Lying down, especially in a position of comfort or rest; reclining.|
|Dorsal recumbent||Lying on the back, as in a supine position.|
Results: Almost 30% (n=99) of the women gave birth with an intact perineum. The incidence of episiotomy for the sample of women was 44% (n= 56) of the 335 women and second degree laceration that needed repair, and 32 women (9.5%) experienced third degree perineal injuries. A chi square test of independence was performed to determine whether a relationship existed between maternal position and perineal outcome. Women giving birth in the birthing bed were more likely to have an intact perineum and less likely to have an episiotomy. Women who delivered in the lithotomy position were more likely to have an episiotomy or third degree perineal injury. There was no statistically significantly relationship between birthing position and perineal outcome for primiparous women. A chi- square test of independence was performed to determine whether a relationship existed between maternal position and perineal outcome. The data indicated a relationship between maternal position and perineal outcome (X 2 =43.34, df=3, p <.05). Women in the birthing bed were more likely to have an intact perineum and less likely to have an episiotomy. Women who delivered in a lithotomy position on the delivery table were more likely to have an episiotomy or third degree perineal injury. The strength of the study is that the number of participants is high, however the study failed to ascertain whether the episiotomy groups were more likely to be attributable to the same practitioner and whether one practitioner preferred certain positions more so than others. The study failed to have predefined protocols as to when episiotomies would be considered or even excluded as this would reduce bias (Polit & Beck, 2008). This study is useful in reaching out to practitioners outside mainstream obstetrics, namely family practitioners in considering non-supine positions and revisiting need for episiotomies.
The findings of this review suggest some possible benefits for the upright position, with the possibility of increased risk of blood loss greater than 500ml. as a potential adverse effect. The weight of the pregnant uterus can compress the abdominal blood vessels, compromising the mother's circulatory function including uterine blood flow. This may negatively affect the blood flow to the placenta, an idea that is further endorsed by Cyna (2006). Women should be encouraged to give birth in the position they feel most comfortable. Women should be allowed to make informed choices about birth positions in which they might assume. In women without an epidural, a number of observational studies have suggested that delivery in an upright position results in a shorter labor, lower incidence of instrumental deliveries and episiotomies and is a more comfortable delivery position. Chen’s small RCT appears to confirm this as well as De Jonge (2004) and Gupta's (2004) systematic reviews. It has been proposed by Chen (1987) that these benefits are due to a higher resting intrauterine pressure which contributes to the downward delivery force and bearing down forces, as well as contractions of greater intensity. The evidence supporting the all four position for those women experiencing profound back pain with respect to pain reduction is noted. Overall, the evidence is more robust with respect to enhanced pelvimetry, enhanced efficiency with respect to uterine and maternal work in the second stage, shorter duration of the second stage in primips and multips, improved pain control with back pain and reduced perineal trauma in the all fours position and left lateral position. The evidence is less conclusive with respect to perineal trauma and the benefit of internal rotation from an occipitoposterior position to an occipitoanterior position when adopting the all fours position. There is no clear evidence on what laboring women actually prefer or will prefer with non-biased education on their options given the prior evidence. Methodological problems were identified with some of the studies and the appropriateness of a randomized controlled trial to study this subject can be questioned. A cohort study may be a more appropriate methodology, supplemented by a qualitative method to study women's experiences.
Chapter 3: Manuscript development
A manuscript option was decided upon to help impart knowledge to all obstetric health care providers of the importance of empowering women and their families to make informed choices about birthing positions based on the current research and to promote and support a natural approach to normal childbirth.
The increasing medicalization of childbirth leads many women assuming that labor is an illness and therefore the ideal place to deliver is within hospital, in bed, in the supine position. This impression is further heightened where the delivery environment is not conducive to alternative positions and the delivery bed remains the central focus in many hospital delivery rooms. The routine use of the supine position can be seen as an intervention in the natural course of labor, which was introduced without evidence of its advantages compared to other positions (De Jonge et al., 2008).
Following research in to options for potential publication possibilities for manuscripts, research was undertaken in to several midwifery and women's health related journals and on line sources to be able to compare the journals, submission requirements and their publication audience. The Journal of Midwifery and Women's Health. (JMWH), American Journal of Maternity, Midwives Information and Resource Service (MIDIRS), Web MD, were some of the resources researched as potential possibilities for publication.
As a novice entering the world of publication possibilities, goals need to be realistic. The underlying objective is to educate a diverse population of readers regarding maternal positions in labor. The manuscript can help facilitate choice for women where they may wish to adopt a variety of positions during labor and birth.
Midwifery Today (MT) is a journal that includes International Midwife, a quarterly publication for birth practitioners. Midwifery Today is not as rigorous in their peer review process because their focus is different than pure or applied science and a different standard is applied. The journal has an emphasis on natural childbirth, breast-feeding, networking and education for midwives. The journal is appealing to midwives, student midwives, doulas, childbirth educators and women and their partners who want a more natural and holistic approach to childbirth (Midwifery Today, 2010). MT mentions their aim is to foster communication between practitioners and families and to promote responsible midwifery and childbirth. MT seeks a balance between scientific or technical material, and considers submissions on all aspects of pregnancy and childbirth. When submitting an instructive article aimed at midwifery procedure or practice, work needs to be factual and accurate.
Midwifery Today publishes articles from all over the world. Ninety-five percent of what is published is original although occasionally reprints from other publications are used. Most of the writers are midwives, doctors, doulas, childbirth educator’s academics or other specialists.
Guidelines include an editorial style sheet and sample references for preferred reference format and general style guides. An APA style is used. See appendix A for publishing guidelines.
Articles can be sent via e mail, mail address or via electronic version on a disk. Previously published articles will not be considered.
The Editorial Board of Midwifery welcomes manuscripts that address pregnancy, birth and postpartum subjects that are directed toward midwives, student midwives, doulas, childbirth educators or their clients. Manuscripts are reviewed by the editor and rate of acceptance depends on quality of article and relevancy of subject (MT, 2010).
Factors Influencing Maternal Positions During Labor
The birth of a child is one of the most significant events in a woman’s life. Practices associated with childbirth are therefore important to the woman’s health and well-being. Research indicates that left to their own devices women will choose a variety of movements and positions to cope with labor (Simkin, 2002; Declercq et al., 2006).
Standing, walking, rhythmic swaying, leaning forward, and assuming the hands and knees position are examples of movements and positions that women instinctively use in response to pain or other sensations during labor. (See diagram of maternal positions in labor)
Provider preferences, restrictive hospital policies, fetal monitoring and epidural analgesia result in many women spending most of their labors and birth in bed, often in the supine position.
The majority of women in Western societies deliver in a supine position. It is claimed that the supine position enables the midwife or obstetrician to monitor the fetus better and thus to ensure a safe birth however, this view ignores the comfort and optimal physiological functioning of the mother which in turn preserves fetal health (Gupta, 2004).
Women's health practitioners have an obligation to teach women and their partners how to find and determine the quality of evidence based information in order to make informed choices this can be achieved by giving practical, supportive advice during pregnancy and labor.
This article aims to look at factors that influence maternal positions in labor and review current evidence regarding their use.
Throughout history women in most cultures have used both the upright position and alternative positions to give birth to babies. (Gupta, 2004).Not until the seventeenth century with the advancement of technology in the form of forceps deliveries were women depicted giving birth in the supine position. (Boyle, 2000).
The supine position became increasingly popular within western societies as the standard position during labor. In the early 18th Century, a prominent French physician, Francois Mauriceau, introduced the supine positions to facilitate the care of the women and to enhance obstetric performance and maneuvers. The supine position then became largely adopted throughout western countries (Diaz et al., 1980). Prior to the 20th century, birth was viewed as a normal process, it most often took place in the home and was a social and emotional event shared by the woman and her family (Zwelling, 2008).In the last century, childbirth has progressively moved from a woman supported experience in the home to a medical intervention in the hospital (Albers, 2007).
During the early 20th century the hospital became the preferred site for birth. Lying down in labor was routine practice in many hospitals (Gupta et al., 2004). Many health professionals today, mistakenly, continue to view the supine position as advantageous, facilitating the midwife or obstetrician to monitor progression and check the baby more effectively and so ensure a safer birth. The current research available in fact calls this view in to question (Lawrence et al., 2009).
Mechanism of Labor
An understanding of the effects of various maternal postures on labor and birth begins with an understanding of the physiologic consequences of assuming specific postures and a review of the mechanics of labor. The mechanism of labor refers to the movements made by the fetus during the first and second stage of labor. As the force of the uterine contractions stimulates effacement and dilatation of the cervix, the fetus moves toward the cervix. When the presenting part reaches the pelvic bones, it must make adjustments to pass through the pelvis and down the birth canal (Gabbe et al., 2007).
The first stage begins with regular uterine contractions and ends with complete cervical dilatation at 10 cm (Gabbe et al., 2007).
An upright position in the first stage is defined as any position that avoids lying flat and may include ambulation. See diagram of maternal positions in labor.
Factors such as the ability to maintain some level of autonomy, ability to mobilize and change positions unprompted, in an environment conducive to welcoming partners and family members are important contributions to patient satisfaction (Albers, 1997; Hodnett, 2007). Patient satisfaction plays a significant role in determining the pattern of one's health seeking behavior in the future. Upright positions and mobility are often more pleasant for laboring women and have distinct advantages in promoting progress leading to a spontaneous vaginal birth (Albers, 1997). Women need to be made aware of alternative positions and advantages and disadvantages in order for them to make an informed choice. A woman lying down or semi reclining on their side or back in the first stage of labor may be more convenient for staff and can allow easier monitoring of progression, such as performing vaginal examinations, checking baby’s position and listening to the fetal heart rate (Gupta, 2004).See table 7 for factors influencing maternal positions in labor. Research findings indicated that contractions increased in strength in the upright or lateral position compared to the supine position and were negatively affected when a laboring woman lay down (Lawrence, 2009).
|FACTORS THAT INFLUENCE MATERNAL POSITIONS IN LABOR|
|Maternal preference |
Other support personnel (partner, doula)
|Health provider preference|
|Health provider training|
|Birthing environment (Home, Birthing Center, Hospital)|
|Analgesia choice (epidural, narcotics)|
|Fetal monitoring method |
TABLE 7: Factors that influence maternal positions in labor
Albers (1997) found that moving in labor can increase a woman’s sense of control by providing a self regulated distraction from the challenge of labor. Increasing a woman’s sense of control may also have the effect of reducing the need for analgesia (Albers, 1997; Hodnett, 2007). This is further supported by Simkin, (2002) who suggests that the upright position in the first stage of labor may increase a woman’s comfort.
Upright positions and walking are associated with a reduction in the length of the first stage of labor and women maybe less likely to have epidural analgesia. Women should be encouraged to adapt whatever position they find most comfortable while avoiding spending long periods in the supine position. Women’s preferences may change during labor, whilst many may choose an upright position in the first stage they may choose to lie down as their labor progresses. Earlier studies have suggested that as a woman reaches five to six centimeters dilatation, there is a preference to lie down (Williams 1980; Roberts 1984).This suggests that there may not be a universal position for women in the first stage of labor (Lawrence, 2009).
Patient controlled epidural analgesia top ups with maternal mobility may be beneficial to the fetus by reducing the hypotension associated with top ups in the lying position (Al-Mufti et al., 2007). Women in labor typically enter an unfamiliar, busy institutional setting to receive care from an array of busy strangers, where numerous technical care measures are routinely used, such as continuous electronic fetal monitoring and epidural analgesia. Intravenous infusions during labor, which are mobility limiting and often create concerns about the intravenous infusions over that of the woman, have become a routine procedure for a high percentage of women in labor throughout the United States, these procedures may affect a woman's mobility and use of postural coping strategies in labor (Spiby et al., 2003; Lawrence, 2009).
The second stage begins with complete cervical dilatation and ends with the delivery of the fetus (Gabbe et al., 2007).
Upright positions in the second stage include sitting more than 45 degree from the horizontal position, use of a birthing chair or ball, squatting or kneeling and being on hands and knees. Recumbent positions include supine, lateral, lithotomy and semi recumbent using pillows and wedges. See diagram of maternal positions in labor.
Maternal body positions have a significant influence on the course of labor, affecting maternal comfort and physiology. The ability to move and adopt positions during labor has been shown to help facilitate labor progress and decrease pain (Ragner et al., 2006; Declercq et al., 2006).
Use of the left lateral position appears to protect the perineum and may prove comforting following long periods in an upright position. Further studies indicated that contractions increased in the lateral and upright positions (Roberts, 1984; Walsh 2000). Squatting using a birthing chair, although reportedly widening the pelvic diameter, thereby creating more room for the baby to descend has also been reported as a predisposing factor for third and fourth degree tears (Albers, 2003; Soong & Barnes, 2005).Kneeling on all fours, side lying and semi sitting allows women to rest between contractions and help conserve energy during contractions.
Physical benefits that have been associated with the non supine positions include stronger and more efficient uterine contractions, aiding cervical dilatation and therefore reduced risk of labor dystocia , utilization of gravity may improve fetal descent and more effective bearing down effects; improved fetal positioning, reduced risk of aorta caval compression and therefore improved acid base outcomes in the newborns and increased diameters of the pelvis, psychological benefits include reduced pain/backache, increased feeling of being in control and more effective communication with health professionals (Simkin & O'Hara, 2002;De Jonge et al, 2004; Gupta, 2004; Soong, 2005; Stremler,2005; Altman, 2006; Declercq et al.,2006, De Jonge et al., 2007; Lawrence et al., 2009).
Radiological evidence of the larger anterioposterior and transverse pelvic outlet diameters results in an increase in the total outlet area in both the squatting and kneeling position (Michel et al., 2002).
Women should be encouraged to take up whatever position they find most comfortable during labor. The benefits of upright posture include a shorter second stage of labor, a small reduction in assisted deliveries, and a decreased episiotomy rate but an increased risk of severe blood loss. Further research indicates that an upright position does not appear to be associated with increased intervention or negative effects on the mothers' and babies' well-being (Mayberry et al., 2003; Gupta et al., 2006). Birth position is influenced by many factors and the research investigating women's perceptions of comfortable positioning, and the extents to which women are influenced in relation to birth position are important contributions to the knowledge on the topic.
The majority of women in Western societies deliver in a supine position. It is claimed that the supine position enables the midwife or obstetrician to monitor the fetus better and thus to ensure a safe birth however, this view ignores the comfort and optimal physiological functioning of the mother which in turn preserves fetal health (Gupta, 2004).There is controversy around whether being upright or lying down has advantages for women delivering their babies. Several physiological advantages have been claimed for non recumbent or upright labor. Table 8 below shows benefits and risks of the non supine position for labor and birth.
| BENEFITS:|| RISKS:|
| Increased diameters of pelvic inlet and outlet|| Increase in second degree tears|
| Improved uterine contractility|| Increase blood loss > 500 mls|
| Improved fetal well being|| Practitioner resistance|
| Reduced duration of second stage labor|| Maternal fatigue|
| Reduction in assisted deliveries|| High dose epidural block|
| Reduction in episiotomies|
| Decreased pain|
|Increased feeling of maternal control|
Increased partner involvement
TABLE 8: BENEFITS & RISKS OF THE NON-SUPINE POSITION FOR LABOR & BIRTH
According to De Jonge (2004) the advice given by midwives as well as the environment in which the woman labors and gives birth are the most important factors influencing the choice of birthing positions. Many women will choose to labor in a recumbent or semi recumbent position because this is what they believe is expected of them, both culturally and socially. If the only furniture available in a hospital labor room is a bed that is what the woman will use. Hospital obstetric departments are often not set up to accommodate alternate positions; with the bed often being the only furniture provided for women. Comfortable chairs, birthing balls, beanbags and furniture to accommodate the upright position such as wall bars, will enable women to choose a variety of positions
(see diagram of maternal positions in labor).
MATERNAL POSITIONS IN LABOR
(Copyright :The Labor Progress Handbook Simkin & Ancheta 2002).
Cultural influences on maternal position
Women use various positions, supine and non supine, if they are left to choose (De Jonge, 2004).The supine position has become so common that neither health care workers nor women regard this as an intervention (De Jonge, 2004). The promotion of hospital as the favored location of birth has meant that women tend to automatically assume labor as an illness; the impression is further heightened where the delivery bed remains the central focus in most delivery rooms. This is further supported by Albers (2007); Jonge et al, (2008) who mention, that action such as the environment and views of health practitioners can influence a woman's choice of labor position.
Where women are able to labor in their own home or a less medicalised environment, they are frequently observed to instinctively adopt a range of alternative positions and therefore maintain greater mobility. (Lawrence et al., 2009).The common use of routine technological interventions during labor, such as electronic fetal monitoring and methods of pain relief such as spinal epidural analgesia and intravenous infusions such as those used for induction of labor affect a woman's mobility and use of postural change in labor (Spiby et al., 2003).
Midwives generally encourage laboring women to be mobile as long as possible and to adopt whatever position is most comfortable, however, there are indications and contraindications for the use of certain positions during the course of labor. Modifying intrapartum care to reflect current evidence, regarding the factors that influence maternal positions in labor, will improve the maternity care that women and families receive. Health professionals working in obstetric care need to be aware of the evidence based practice regarding maternal positions in labor to enable women to make informed choices.
Women's health practitioners have an obligation to teach women and their partners' how to find and determine the quality of evidence based information in order to make informed choices.
Most women have the potential to have a physiologic labor and birth; one that starts and proceeds on its own, without routine use of interventions or drugs (Albers, 2007).
Factors such as the ability to maintain some level of autonomy, ability to mobilize and change positions unprompted, in an environment conducive to welcoming partners and family members are important contributions to patient satisfaction. Patient satisfaction plays a significant role in determining the pattern of one's health seeking behavior in the future. Upright positions and mobility are often more pleasant for laboring women and have distinct advantages in promoting progress leading to a spontaneous vaginal birth. Women need to be made aware of alternative positions and advantages and disadvantages in order for them to make an informed choice. Women should be encouraged to give birth in positions that they find comfortable while avoiding spending long periods in a supine position. Midwives are in a unique position to provide evidence-based care that promotes normal birth and provides healthy outcomes.
Adachi, K., Shimada, M., Usui, A. (2003). The relationship between the parturient positions and perceptions of labor pain intensity. Nursing Research 52, 47-51.
Albers, L. (2007). The evidence for physiologic management of the active phase of the first stage of labor. Journal of Midwifery and Women’s Health. 52:207-215.
Altman, M.R., Lydon-Rochelle, M.T. (2006). Prolonged second stage of labor and risk of adverse maternal and perinatal outcomes: a systemic review. Birth Issues in Perinatal Care 33(4), 315-322.
Al-Mufti, R. (1997). Blood Pressure and fetal heart rate changes with patient controlled combined spinal epidural analgesia while ambulating in labor. British Journal of Obstetrics and Gynecology.104, 554-558.
American College of Nurse-Midwives (1997). Definition of Midwifery Practice. Washington, DC: ACNM. Retrieved October 8, 2009, from http://www.midwife.org/about midwife profession.
Boyle, M. (2000). Childbirth in bed. The historical prospective. Practical Midwife 3:21-4.
Chen, S, Z., Aisaka, K., Hiroyuki, H., Kigawa, T. (1987). Effects of sitting position on uterine activity during labor. Journal of Nurse Midwifery 69, 67-73.
Declercq, E. R., Sakala, C., Corry, M. P., Applebaum, S. (2006).Listening to Mother's II: Report of the second national U.S. survey of women's childbearing experiences. New York: Childbirth Connection.
De Jonge, A., Largo-Janssen, A.L.M. (2004). Birthing Positions. A qualitative study in to the views of women about various birthing positions. Journal of Psychosomatic Obstetrics and Gynecology.25, 47-56.
De Jonge, A., Doreth, A.M., Teunissen, M. T., Diem, M. T., Peer L. H., Scheepers P.L.H., & Largo-Janssen A.L.M. (2008). Women’s positions during the second stage of labor: views of primary care midwives. Journal of Advanced Nursing.10, 347-356.
De Jong, P., R.Johanson, R.B., Baxen, P., Adrians, V.D., Westhuisen, S., Jones (1997). Randomized trial comparing the upright and supine positions for the second stage of labor. British Journal of Obstetrics and Gynecology 104,567-571.
Diaz, A. G., Schwarcz, R., Caldeyro-Barcia. R. (1980). Vertical position during the first stage of labor, and neonatal outcome. European Journal Obstetrics and Gyn Reproductive Biol. 11 (1):1-7.
Gabbe, S.,G., Niebyl, J.R., Simpson, J. L. (2007) Obstetrics Normal and problem pregnancies. (5th Ed.).Philadelphia: Churchill Livingstone.
Gupta, J. K., Hofmeyr, G., Smith, R. (2004). Position for women during second stage of labor for women without epidural anesthesia. The Cochrane Library, Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
Hodnett, E. D.,Gates, S., Hofmeyer, G. J., Sakala, C. (2007). Continuous support for women during childbirth. Cochrane Database of Systematic Reviews, Issue 3( DOI:101002/14651858. CD003766.pub2).
Jonge, A., Doreth, A.M., Teunissen, M. T., Diem, M. T., Peer L. H., Scheepers P.L.H., & Largo-Janssen A.L.M. (2008). Women’s positions during the second stage of labor: views of primary care midwives. Journal of Advanced Nursing, 10, 347-356.
Jonge, A., Teunissen, T., Largo-Janssen, A. (2004). Supine Position Compared to other positions during the second stage of labor: A meta-analytic review. Journal of Psychosomatic Obstetrics & Gynecology 25:35-42.
Lawrence, A., Hofmeyer, L. L., Dowsell, T., Styles, C. (2009). Maternal positions and mobility during first stage labor (Review).The Cochrane Collaboration.Wiley & Sons ltd. (4).
Mayberry, L., Strange, L.,B., Suplee, P. D., Gennaro, S.(2003).Use of upright positioning with epidural analgesia. American Journal of Maternal and Child Nursing, 28, 152-159.
Michel, S.C.A., Rake, A., Treiber, K., Seifert, B., Chaoui, R., Hutch, R., Marineck, B. & Kubik-Hutch R. A. (2002). MR Obstetric Pelvimetry: Effect of birthing position on pelvic bony dimensions. American Journal of Roentgenology 179, 1063-1067.
Midwifery Today (2010).Retrieved February 17, 2010 from: http://www. midwiferytoday.com
National Center for Health Statistics. Birth statistics. (2007). Retrieved October 8, 2009, from http://www.cdc.gov/nchs/vitalstats.htm.
O’Sullivan, G., Liu, B., Hart, D., Seed, P., Shennan, A. (2009). Effect of food intake during labor on obstetric outcome: randomized controlled trial. British Medical Journal. 338:784.
Polit, D. F., Beck, C.T. (2008).Nursing Research. Generating and Assessing Evidence for Nursing Practice, (8th Ed.) Lippincott Williams and Wilkins. New York.
Polit, D., Beck, C., Hungler, B., (2001).Essentials of nursing research. Methods, appraisal, and utilization. (5th Ed.).Philadelphia: Lippincott.
Roberts, J, E., Mendez-Bauer, C.,Blackwell, J.,Carpenter, M,E., Marchese,T (1984). Effects of lateral recumbencyand sitting on the first stageof labor. Journal of Reproductive Medicine.
Romano, A., Lothian, J. (2006). Protecting, promoting and supporting normal birth. The evidence basis for six care practices. Journal of Perinatal Education, 13, (2), 1-5.
Russell, J. G. (1969). Molding of the pelvic outlet Journal of Obstetrics & Gynecology British Commonwealth 76:817-820.
Soong, B., Barnes, M. (2005). Maternal Position at midwife attended birth and perineal trauma: Is there an association? Birth 32:3,164-169.
Simkin, P., Ancheta, R. (2002). The labor progress handbook. Malden, MA: Blackwell Sciences.
Spiby, H., Slade, P., Escott, D., Henderson, B., Fraser, R., B. (2003). Selected coping strategies in labor: an investigation of women’s experiences. Birth. 30: 189-194.
Soong, B., Barnes, M. (2005). Maternal Position at midwife attended birth and perineal trauma: Is there an association? Birth 32:3,164-169.
Stremler, R., Hodnett, E., Petryshen, P., Stevens, B., Weston, J, .Willan, A, R. (2005). Randomized controlled trial of hands and knees positioning for occipitoposterior position in labor. Birth 32:4, 243-251.
Varney, H., Kriebs, J, .M. Gegor, C. (2004). Varney’s Midwifery. 4th Ed. Jones and Bartlett Publishers. Sudbury, Ma.
Williams, R, M.,Thom, M., Studd, J. (1980). A study of the benefits and acceptability of ambulation in spontaneous labor.British Journal of Obstetrics and Gynaecology. 87:122-6
Zwelling, E. (2008). The Emergence of High -Tech Birthing. Journal of Obstetric Gynecologic and Neonatal Nursing, 37: 85-93.
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