Lamaze International's popular series, Research Summaries for Normal Birth, was discontinued in 2008 after four years of quarterly round-ups so that we could move to the blog format and launch Science & Sensibility. In order to bring all of our research resources together in one place, we are adding the Research Summaries archive to Science & Sensibility.

This week we are presenting the archive of summaries of research on care in the second stage of labor. Don't forget that you can find all second stage Science & Sensibility posts (including this archive) by clicking on 'second stage' in the tag cloud.

The articles summarized in this archive are listed here. Please click on the extended post to read the summaries.

1. Digital Rotation When the Baby is OP Decreases Need for Cesarean Section and Instrumental Vaginal Delivery
   Reichman, O., Gdansky, E., Latinsky, B., Labi, S., & Samueloff, A. (2007). Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section. European Journal of Obstetrics, Gynecology, and Reproductive Biology, 10.1016/j.ejogrb.2006.12.025.
2. Coached Pushing Offers No Benefit to Moms or Babies and May Be Harmful
   Bloom, S. L., Casey, B. M., Schaffer, J. I., McIntire, D. D., Leveno, K. J. (2006). A randomized trial of coached versus uncoached maternal pushing during the second stage of labor. American Journal of Obstetrics and Gynecology, 194, 10-3.
3. Upright Positions in Second Stage May Decrease Instrumental Deliveries in Women with Epidural Analgesia
   Roberts, C. L., Algert, C. S., Cameron, C. A., & Torvaldsen, S. (2005). A meta-analysis of upright positions in the second stage to reduce instrumental deliveries in women with epidural analgesia. Acta Obstetricia et Gynecologica Scandinavica, 84(8), 794-798.
4. Delayed, 'Physiologic' Pushing Improves Fetal Oxygenation in Women Using Epidural Analgesia
   JSimpson, K. R., & James, D. C. (2005). Effects of immediate versus delayed pushing during second-stage labor on fetal well-being: a randomized clinical trial. Nursing Research, 54(3), 149-157.

1. Digital Rotation When the Baby is OP Decreases Need for Cesarean Section and Instrumental Vaginal Delivery
Reichman O, Gdansky E, Latinsky B, Labi S, & Samueloff A (2008). Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section. European journal of obstetrics, gynecology, and reproductive biology, 136 (1), 25-8 PMID: 17368909

Summary: In this prospective, controlled trial, researchers studied the effect of digital or manual rotation of the fetal head from occipito-posterior (OP) to occipito-anterior (OA) on mode of birth, position of the baby at birth, length of hospital stay, perineal integrity, Apgar score, and other obstetric and neonatal outcomes. Digital rotation is a technique where the physician or midwife applies pressure with the fingertips against the baby's head to help it turn to a more favorable position. Manual rotation is a variant using the practitioner's whole hand.

Nulliparous women were eligible for the study if they were in labor at term, the baby was engaged in the OP position, and at least one hour of second stage had elapsed (90 minutes if the woman had an epidural). Multiparous women had to meet the same criteria except that they were eligible after 30 minutes of second stage labor (1 hour if using an epidural). Women carrying a suspected macrosomic baby or who had previously had cesarean surgery were excluded. During the first six months of the study, 30 women were enrolled in the study as controls: they met study eligibility requirements but did not undergo digital rotation. In the second six month period, 31 women (the rotation group) met eligibility requirements and underwent digital or manual rotation of the fetal head by a physician or midwife experienced in the technique. Researchers confirmed OP position by ultrasound in the rotation group but relied on digital examination alone for the control group. While digital examination is not as reliable as ultrasound in the diagnosis of OP position, 85% of the babies in the control group eventually gave birth to a baby who was OP, suggesting that the diagnosis was accurate at least 85% of the time. To avoid possible bias, the clinicians who performed rotations did not participate in the woman's care thereafter.

Among women who underwent digital or manual rotation, 77% had spontaneous vaginal births compared with only 26% of those in the control group. They were also much more likely to give birth (regardless of mode of birth) to babies in the OA position (93% vs. 15%). None of the women who underwent rotation had a cesarean delivery compared with 23% of those who did not undergo rotation and vacuum-assisted delivery was also significantly less likely, with 23% in the rotation group versus 50% in the control group. All of these differences were highly statistically significant (very unlikely to be the result of chance). Duration of second stage was an average of 39 minutes shorter and the women were discharged almost a day earlier in the rotation group. Episiotomy was significantly more likely in the control group (65% versus 30%) Other outcomes, such as low Apgar scores and likelihood of postpartum hemorrhage or infection, were similar across the two groups, although the study was too small to detect differences in uncommon adverse outcomes.

Significance for Normal Birth: When a baby is engaged in a posterior (OP) position during the second stage of labor, a large body of research suggests that the likelihood of vaginal birth is highly dependent on whether the baby rotates to an anterior (OA) position. Maternal hands-and-knees positioning has been associated with successful rotation to OA in at least one trial (Stremler, Hodnett, Petryshen, Stevens, Weston, & Willan, 2005) but may be difficult for women using an epidural, which sharply increases the chance of persistent OP (Lieberman, Davidson, Lee-Parritz, & Shearer, 2005). Forceps rotation is also effective but is risky for both the mother and the baby. Some practitioners perform vacuum-assisted rotations but this method has not been studied for safety and there is anecdotal evidence of harm (Society of Obstetricians and Gynaecologists of Canada, 2005). This trial provides evidence that manual and digital rotation are effective alternatives to instrumental rotation, and while larger studies are needed to have complete confidence about safety, this uncertainty must be balanced against the known harms of cesarean surgery, instrumental vaginal deliveries, and episiotomies.

While digital rotation is a relatively straightforward procedure, it is still considered among the obstetric 'arts' in that it is a skill honed through experience that not every practitioner possesses. However, this study suggests that many if not most cesarean sections and instrumental vaginal births for persistent posterior position in second stage can be safely prevented with digital rotation. If a laboring woman is presented with the need for an operative delivery for prolonged second stage in the presence of fetal malposition, she should be informed that digital rotation is a low-risk alternative and arrangements should be made to provide access to a practitioner who can perform it if hers is unable. Pregnant women should also be advised that epidural analgesia can increase the likelihood of persistent malposition and of the potential consequences of this complication.

References:
Lieberman, E., Davidson, K., Lee-Parritz, A., & Shearer, E. (2005). Changes in fetal position during labor and their association with epidural analgesia. Obstetrics and Gynecology, 105(5 Pt 1), 974-982.

Society of Obstetricians and Gynaecologists of Canada. (2005). Guidelines for operative vaginal birth. Number 148, May 2004. International Journal of Gynaecology and Obstetrics, 88(2), 229-236.

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.

2. Coached Pushing Offers No Benefit to Moms or Babies and May Be Harmful
Bloom SL, Casey BM, Schaffer JI, McIntire DD, & Leveno KJ (2006). A randomized trial of coached versus uncoached maternal pushing during the second stage of labor. American journal of obstetrics and gynecology, 194 (1), 10-3 PMID: 16389004

Summary: This randomized controlled trial evaluated the impact on perinatal outcomes of coached versus uncoached pushing during the second stage of labor. Nulliparous women with low-risk, term pregnancies in spontaneous labor without epidural analgesia were included in the study. About half of the participants (n=163) were randomized to coached pushing with a closed glottis (i.e., while holding one's breath), while the other half (n=157) were not given any specific instruction on how to push. Both groups were attended by certified nurse-midwives throughout labor and birth.

The average length of second stage was 13 minutes shorter in the coached pushing group (46 minutes versus 59 minutes, p=.014), however there was no significant difference in the likelihood of pushing beyond 2 hours or 3 hours. No other statistically or clinically significant differences in mode of birth, perineal integrity, or neonatal outcome were found between the two groups.

Significance for Normal Birth: Coached pushing provided no clinically important benefits in this well designed trial. Previous research has suggested that coached pushing may be harmful to the woman's pelvic floor muscles and may be associated with adverse neonatal outcomes. The widespread use of coached pushing undermines women's intrinsic knowledge of how to give birth safely and gently. In the absence of evidence that this practice is beneficial and with mounting evidence that it may contribute to poor perinatal outcomes, routine use of coached pushing should be abandoned.

This study is an important addition to the literature because it evaluates coached versus physiologic pushing in the absence of epidural analgesia, which complicates second stage management. Previous research has shown that coached pushing is associated with poor perinatal outcomes when an epidural is used.

3. Upright Positions in Second Stage May Decrease Instrumental Deliveries in Women with Epidural Analgesia
Roberts CL, Algert CS, Cameron CA, & Torvaldsen S (2005). A meta-analysis of upright positions in the second stage to reduce instrumental deliveries in women with epidural analgesia. Acta obstetricia et gynecologica Scandinavica, 84 (8), 794-8 PMID: 16026407

Summary: This meta-analysis assessed the effectiveness of upright positions during the second stage of labor for lowering the risk of instrumental vaginal delivery in women using epidural analgesia. The researchers conducted a systematic review of the literature using pre-specified criteria to identify relevant randomized controlled trials (RCTs). Data from included studies were combined into a new dataset and analyzed using standard statistical methods for meta-analysis.

Differences in outcomes between women using upright positions in the second stage of labor and those assigned to recumbent positions failed to reach statistical significance because of the small size of the studies, variation in study definitions of upright positions, differences in what outcomes were reported and compliance with randomization,. However, statistically non-significant differences were found in the rates of instrumental birth, cesarean section, perineal trauma and length of labor - all favoring the use of upright positions. Differences across the two groups in rates of instrumental and cesarean birth were large. No differences were found in any infant outcomes. The authors conclude that 'the results of this meta-analysis...are inconclusive, but encouraging enough to justify a full-sized trial that could determine whether the observed effects are real or chance findings.'

Significance for Normal Birth: Upright positions in birth have been used throughout history and across cultures because they use gravity to help the baby descend and tend to be less painful than supine positions, where the woman lays on her back. Studies of upright positions report lower rates of obstetric interventions, especially instrumental delivery. Because epidural use is associated with a higher rate of instrumental deliveries in nulliparous women, it is likely that encouraging upright positions may help women choosing epidural analgesia achieve spontaneous vaginal births and avoid the risks associated with instrumental delivery. These include injury to the pelvic floor muscles, a complication associated with bowel and bladder incontinence. While this meta-analysis failed to detect statistically significant differences in the mode of birth between women in upright and supine positions, these results are likely due to methodological flaws and weaknesses of the included studies. A well-designed RCT is needed to further clarify this issue.

4. Delayed, 'Physiologic' Pushing Improves Fetal Oxygenation in Women Using Epidural Analgesia
Simpson KR, & James DC (2005). Effects of immediate versus delayed pushing during second-stage labor on fetal well-being: a randomized clinical trial. Nursing research, 54 (3), 149-57 PMID: 15897790

Summary: This randomized controlled trial compared the effects on fetal wellbeing of two different approaches to the management of the second stage of labor in nulliparous women with epidural analgesia. Women in an immediate pushing group began pushing as soon as they were 10 cm. dilated and were coached by a nurse to hold their breath (closed-glottis) and push for 10 seconds 3-4 times per contraction with every contraction until birth. Women in a delayed pushing group remained on their left side from the time they reached 10 cm of dilation until they felt the urge to push or until 2 hours had passed (whichever came first). At that time, they were encouraged to bear down without holding their breath (o! pen-glottis) for no more than 6-8 seconds at a time no more than 3 times per contraction until birth. Fetal well being was monitored using internal fetal oxygen saturation (FSpO2) sensors and continuous electronic fetal heart rate (FHR) monitoring. FSpO2 values <30% are abnormal and are considered clinically significant (i.e. contribute to poor neonatal outcomes) when fetal oxygen saturation remains this low for >2 min. during labor.

Fetal oxygen desaturation events lasting >2 minutes occurred significantly more frequently in the immediate pushing group than in the delayed pushing group (mean of 7.9 events versus 2.7 events, p=.02). The mean oxygen saturation decreased significantly over the course of second stage in both groups, however women in the delayed pushing group had significantly smaller changes in fetal oxygen saturation during second stage. This difference persisted even when researchers controlled for the length of second stage and the presence of a nuchal cord (umbilical cord wrapped around the neck). There were also significant differences between the two groups in the rates of variable and prolonged FHR decelerations. No differences were found in other measures of fetal wellbeing or in newborn outcomes such as Apgar scores.

The second stage of labor was significantly longer in the delayed pushing group (mean 139 minutes versus 101 minutes, p=.01). However, the average length of active pushing was significantly longer in the immediate pushing group (mean =101 minutes versus 59 minutes, p=.002). This is significant because 94% of instances of fetal oxygen desaturation lasting >2 minutes occurred during active pushing, with the remainder occurring during passive decent in the delayed pushing group. Significantly more women in the immediate pushing group had perineal lacerations (13 versus 5, p=.01). Other maternal outcomes, including rates of instrumental or cesarean birth and episiotomy, were similar between the two groups.

Significance for Normal Birth: RCTs show that physiologic pushing, that is, bearing down instinctively with the natural urges and without holding one's breath is easier on the baby and equally effective when compared with directed pushing, that is, bearing down on command while holding one's breath beginning at full dilation. Despite this, closed-glottis pushing is used routinely in many birth settings, even in women using epidural analgesia, which can delay the woman's urge to bear down and prolong the second stage. The attempt to hurry second stage may have arisen because many birth settings impose arbitrary time limits on the length of second stage. This study shows that despite the increased duration of second stage, delayed, physiologic pushing should be used when a nulliparous woman has an epidural in order to optimize fetal wellbeing and lower the woman's risk of perineal trauma.

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