When to stop pushing: effects of duration of second-stage expulsion efforts on maternal and neonatal outcomes in nulliparous women with epidural analgesia

[Indications of primary cesarean deliveries in a regional teaching hospital and reasonable strategies for reducing them]

OBJECTIVES

To characterize the indications of primary cesarean sections and discuss the various possibilities to reduce them.

MATERIALS AND METHODS

Retrospective study, carried out over a period of 1 year in a university hospital having a level 3 perinatal activity, including the 499 primary cesarean sections of 2013. Two groups were defined by parity: nulliparous patients (group 1) and multiparous patients who had never previously been delivered by cesarean section (group 2). We have assessed the indication of every primary cesarean section and health status of newborns in each group.

RESULTS

Groups 1 and 2 respectively included 369 and 130 patients. The cesarean section rate in 2013 was 24.7% with a primary cesarean section rate of 17%. Seventy-four percent of the primary caesarean deliveries were performed on nulliparous women and 26% on multiparous (P<0.001). Sixty-three percent of the primary caesarean deliveries were performed on nulliparous women with a singleton fetus in cephalic presentation. The most common indications for primary cesarean delivery were non-reassuring fetal heart rate tracing (47.1%), failure to progress (24.8%) for which nulliparous women were more involved (29% vs. 13%, P<0.001) and fetal malpresentation (9.6%).

CONCLUSION

Further analysis of fetal heart rate during labor, a larger use of second line means to evaluate the fetal status during labor, using 6cm as the cut off for active labor, and encouraging vaginal operative delivery constitute the best way to decrease the primary cesarean section rate.

Second-stage labor: how long is too long?

The management of labor has come under increased scrutiny due to the rapid escalation of cesarean delivery in the United States. A workshop of the Society for Maternal-Fetal Medicine, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the American Congress of Obstetricians and Gynecologists was convened to address the rising cesarean delivery rates and one of their recommendations was that the accepted upper limit of the second stage of labor should be increased to ≥4 hours in nulliparous women with epidural analgesia and to ≥3 hours in parous women with epidural. This led to the inaugural Obstetric Care Consensus series document, "Safe Prevention of the Primary Cesarean Delivery," wherein the workshop recommendations on second-stage labor were promulgated nationally. The result is that the now acceptable maximum length of the second stage of labor exceeds the obstetric precepts that have been in use for >50 years. In this Clinical Opinion, we review the evidence on infant safety, vis-à-vis length of the second stage of labor. Our examination of the evidence begins at the outset of the 20th century and culminates in the very recent (2014) recommendation to abandon the long accepted obstetric paradigm that second-stage labor >3 hours in nulliparous women with labor epidural is unsafe for the unborn infant. We conclude that the currently available evidence fails to support the Obstetric Care Consensus position that longer second-stage labor is safe for the unborn infant. Indeed, the evidence suggests quite the opposite. We suggest that when infant safety is at stake the evidence should be robust before a new clinical road is taken. The evidence is not robust.

Association of the Duration of Active Pushing With Obstetric Outcomes

OBJECTIVE

To estimate the associations between the duration of active pushing during the second stage of labor and maternal and neonatal outcomes.

METHODS

We performed an observational study in which data were obtained by trained abstractors from maternal and neonatal charts of deliveries at 25 hospitals over a 3-year period. In this secondary analysis, women with no prior cesarean delivery who had a term, singleton, cephalic gestation and reached complete dilation were analyzed. The duration of pushing, defined as the time from initiation of pushing to either vaginal delivery or the decision to proceed with a cesarean delivery, was determined. The primary maternal outcome was cesarean delivery and the primary neonatal outcome was a composite that included: mechanical ventilation, proven sepsis, brachial plexus palsy, clavicular fracture, skull fracture, other fracture, seizures, hypoxic-ischemic encephalopathy, or death. Nulliparous and parous women were analyzed separately in univariable and then multivariable analyses.

RESULTS

A total of 53,285 women were analyzed. In both nulliparous and parous women, longer duration of pushing was associated with increased odds of both cesarean delivery and the neonatal adverse outcome composite. Nevertheless, even after 4 hours of pushing, approximately 78% of nulliparous women who continued with active pushing had a vaginal delivery and more than 97% did not have the composite adverse neonatal outcome. Similarly, after more than 2 hours of pushing, approximately 82% of parous women who continued active pushing delivered vaginally and more than 97% did not have the adverse neonatal outcome.

CONCLUSION

A longer duration of pushing is associated with an increased relative risk, but small absolute difference in risk, of neonatal complications. Approximately 78% of nulliparous women delivered vaginally even after 4 hours of pushing.

Duration of Expulsive Efforts and Risk of Postpartum Hemorrhage in Nulliparous Women: A Population-Based Study

Objective

To assess the specific association between the duration of expulsive efforts and the risk of postpartum hemorrhage.

Methods

Population-based cohort-nested case-control study of nulliparous women delivering vaginally in 106 French maternity units between December 2004 and November 2006, including 3,852 women with PPH (blood loss ≥ 500 mL and/or peripartum Hb decrease ≥ 2 g/dL), 1,048 of them severe (peripartum Hb decrease ≥ 4 g/dL or transfusion of ≥ 2 units of red blood cells), and 762 controls from a representative sample of deliveries without hemorrhage in the same population. The association between duration of expulsive efforts and postpartum hemorrhage was estimated by multilevel logistic regression models adjusted for individual and hospital characteristics.

Results

Median duration of expulsive efforts was 18 minutes among controls, 20 minutes among postpartum hemorrhage and 23 minutes among severe postpartum hemorrhage (p<0.01). Duration of expulsive efforts was significantly, positively, and linearly associated with both postpartum hemorrhage and severe postpartum hemorrhage. After adjustment for other risk factors, every additional 10 minutes of expulsive efforts was associated with about a 10% increase in the risk of postpartum hemorrhage (aOR = 1.11 [1.02–1.21]) and severe postpartum hemorrhage (aOR = 1.14 [1.03–1.27]). Oxytocin during labor, duration of active phase of labor, forceps use, episiotomy, perineal tears, and birth weight were also independently associated with both risks.

Conclusion

Duration of expulsive efforts was independently associated with postpartum hemorrhage and severe postpartum hemorrhage. Interventions to shorten the duration of this stage, such as oxytocin, forceps, and episiotomy, are also associated with higher risks of postpartum hemorrhage. Beyond duration, other aspects of the management of active second stage should be evaluated as some might allow it to last longer with a minimal increase in postpartum hemorrhage risk.

Pushing/bearing down methods for the second stage of labour

BACKGROUND

Maternal pushing during the second stage of labour is an important and indispensable contributor to the involuntary expulsive force developed by uterus contraction. Currently, there is no consensus on an ideal strategy to facilitate these expulsive efforts and there are contradictory results about the influence on mother and fetus.

OBJECTIVES

To evaluate the benefits and possible disadvantages of different kinds of techniques regarding maternal pushing/breathing during the expulsive stage of labour on maternal and fetal outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (28 January 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised assessing the effects of pushing/bearing down techniques (type and/or timing) performed during the second stage of labour on maternal and neonatal outcomes. Cluster-RCTs were eligible for inclusion but none were identified. Studies using a cross-over design and those published in abstract form only were not eligible for inclusion.We considered the following comparisons.Timing of pushing: to compare pushing, which begins as soon as full dilatation has been determined versus pushing which begins after the urge to push is felt.Type of pushing: to compare pushing techniques that involve the 'Valsalva Manoeuvre' versus all other pushing techniques.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias. Two review authors independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included 20 studies in total, seven studies (815 women) comparing spontaneous pushing versus directed pushing, with or without epidural analgesia and 13 studies (2879 women) comparing delayed pushing versus immediate pushing with epidural analgesia. The results come from studies with a high or unclear risk of bias, especially selection bias and selective reporting bias. Comparison 1: types of pushing: spontaneous pushing versus directed pushingOverall, for this comparison there was no difference in the duration of the second stage (mean difference (MD) 11.60 minutes; 95% confidence interval (CI) -4.37 to 27.57, five studies, 598 women, random-effects, I(2): 82%; T(2): 220.06). There was no clear difference in perineal laceration (risk ratio (RR) 0.87; 95% CI 0.45 to 1.66, one study, 320 women) and episiotomy (average RR 1.05 ; 95% CI 0.60 to 1.85, two studies, 420 women, random-effects, I(2) = 81%; T(2) = 0.14). The primary neonatal outcomes such as five-minute Apgar score less than seven was no different between groups (RR 0.35; 95% CI 0.01 to 8.43, one study, 320 infants), and the number of admissions to neonatal intensive care (RR 1.08; 95% CI 0.30 to 3.79, two studies, n = 393) also showed no difference between spontaneous and directed pushing and no data were available on hypoxic ischaemic encephalopathy.The duration of pushing (secondary maternal outcome) was five minutes less for the spontaneous group (MD -5.20 minutes; 95% CI -7.78 to -2.62, one study, 100 women). Comparison 2: timing of pushing: delayed pushing versus immediate pushing (all women with epidural)For the primary maternal outcomes, delayed pushing was associated with an increase of 54 minutes in the duration of the second stage of labour (MD 54.29 minutes; 95% CI 38.14 to 70.43; 10 studies, 2797 women, random-effects; I(2) = 91%; T(2) = 543.38), and there was no difference in perineal laceration (RR 0.94; 95% CI 0.78 to 1.14, seven studies. 2775 women) and episiotomy (RR 0.95; 95% CI 0.87 to 1.04, five studies, 2320 women). Delayed pushing was also associated with a 20-minute decrease in the duration of pushing (MD - 20.10; 95% CI -36.19 to -4.02, 10 studies, 2680 women, random-effects, I(2) = 96%; T(2) = 604.37) and an increase in spontaneous vaginal delivery (RR 1.07; 95% CI 1.03 to 1.11, 12 studies, 3114 women).For the primary neonatal outcomes, there was no difference between groups in admission to neonatal intensive care (RR 0.98; 95% CI 0.67 to 1.41, three studies, n = 2197) and five-minute Apgar score less than seven (RR 0.15; 95% CI 0.01 to 3.00, three studies, n = 413). There were no data on hypoxic ischaemic encephalopathy. Delayed pushing was associated with a greater incidence of low umbilical cord blood pH (RR 2.24; 95% CI 1.37 to 3.68) and increased the cost of intrapartum care by CDN$ 68.22 (MD 68.22, 95% CI 55.37, 81.07, one study, 1862 women).

AUTHORS' CONCLUSIONS

This review is based on a total of 20 included studies that were of a mixed methodological quality.Timing of pushing with epidural is consistent in that delayed pushing leads to a shortening of the actual time pushing and increase of spontaneous vaginal delivery at the expense of an overall longer duration of the second stage of labour and double the risk of a low umbilical cord pH (based only on one study). Nevertheless, there was no difference in the caesarean and instrumental deliveries, perineal laceration and episiotomy, and in the other neonatal outcomes (admission to neonatal intensive care, five-minute Apgar score less than seven and delivery room resuscitation) between delayed and immediate pushing. Futhermore, the adverse effects on maternal pelvic floor is still unclear.Therefore, there is insufficient evidence to justify routine use of any specific timing of pushing since the maternal and neonatal benefits and adverse effects of delayed and immediate pushing are not well established.For the type of pushing, with or without epidural, there is no conclusive evidence to support or refute any specific style or recommendation as part of routine clinical practice. Women should be encouraged to bear down based on their preferences and comfort.In the absence of strong evidence supporting a specific method or timing of pushing, patient preference and clinical situations should guide decisions.Further properly well-designed randomised controlled trials are required to add evidence-based information to the current knowledge. These trials should address clinically important maternal and neonatal outcomes and will provide more complete data to be incorporated into a future update of this review.

Early amplitude-integrated EEG monitoring 6 h after birth predicts long-term neurodevelopment of asphyxiated late preterm infants

The present study aimed to assess the prognostic value of early amplitude-integrated electroencephalogram (aEEG) in late preterm infants who were born at a gestational age between 34 0/7 and 36 6/7 weeks for the prediction of neurobehavioral development. Late preterm infants (n = 170) with normal, mild, and severe asphyxia underwent continuous recording of aEEG for 4-6 h starting 6-8 h after delivery. The recordings were analyzed for background pattern, sleep-wake cycle (SWC), and seizures. Survivors were assessed at 18 months by neurological examination and Bayley Scales of Infant Development II. The incidence of adverse neurological outcome in the asphyxia group was significantly higher than in the normal group. For late preterm infants in the asphyxia group, abnormal aEEG pattern had a predictive potential of neurological outcomes with sensitivity of 78.57% (specificity, 87.80%; positive predictive value [PPV], 68.75%; negative predictive value [NPV], 92.31%; power, 85.45%). Non-SWC and intermediate SWC significantly were increased (25.45 and 52.73%, respectively) in the asphyxia group vs. the normal group. SWC pattern had neurological prognosis value in the asphyxia group with sensitivity of 64.29% (specificity, 87.80%; PPV, 64.29%; NPV, 87.80%; power, 81.82%).

CONCLUSION

Early aEEG patterns are important determinants of long-term prognosis of neurodevelopmental outcome in asphyxiated late preterm infants.

Sonographic pattern of fetal head descent: relationship with duration of active second stage of labor and occiput position at delivery

OBJECTIVES

The objectives of this study were firstly to assess the longitudinal changes of various sonographic parameters of fetal head progression in relation to length of active second stage of labor, and secondly to compare ultrasound findings obtained longitudinally among fetuses with persistent occiput posterior (OP) vs those with persistent occiput anterior (OA) position.

METHODS

From a series of nulliparous low-risk women at term attending the labor ward of our university hospital, transperineal ultrasound volumes were prospectively acquired at the beginning of the active second stage (T1) and at 40-min intervals thereafter until delivery (T2, T3). Sonographic parameters were derived from offline analysis of each volume, including the angle of progression (AoP), progression distance (PD), head-symphysis distance (HSD), head direction (HD) and midline angle. These parameters were compared between patients who delivered within 60 min from the beginning of the active second stage of labor (early delivery) and those who remained undelivered by that time (late delivery). Fetal head position was determined from stored digital images of transabdominal examinations performed at the beginning of the active second stage. Comparison was performed between fetuses with OA and those with persistent OP position at delivery.

RESULTS

Spontaneous vaginal delivery was achieved in 58 (81.7%) cases, whereas vacuum extraction and Cesarean section were performed in eight (11.3%) and five (7.0%) cases, respectively. Delivery was achieved within 60 min from the beginning of the active second stage in 44 (62.0%) patients. In the early vs late delivery groups, measurements of AoP, HSD and PD at T1 were significantly different (AoP, 143.9 ± 20.5° vs 125.3 ± 15.0°, P < 0.001; HSD, 14.8 ± 4.5 mm vs 20.9 ± 5.8 mm, P < 0.001; PD, 44.0 ± 14.1 vs 35.0 ± 13.1 mm, P = 0.008). On logistic regression analysis of data obtained at T1, maternal body mass index, oxytocin administration, neonatal birth weight and HSD appeared to predict independently duration of the active second stage. Among fetuses delivering in the OP position (n = 10, 13.5%), Cesarean delivery was significantly more common than in those delivering in the OA position (n = 5 (50.0%) vs n = 2 (3.1%), P = 0.001). Women with persistent OP position compared with OA showed a significantly different AoP at T1 (122 ± 17° vs 138 ± 20°, P = 0.016), HD and HSD at T1 (HD, 112 ± 17 mm vs 86 ± 19 mm, P < 0.001; HSD, 16.5 ± 5.4 mm vs 22.8 ± 6.6 mm, P = 0.008) and at T2 (HD, 120 ± 16 vs 82 ± 27 mm, P = 0.008; HSD, 12.6 ± 3.4 mm vs 18.5 ± 5.4 mm, P = 0.038).

CONCLUSIONS

AoP, PD and HSD are significantly different between patients undergoing delivery before or after 60 min from the beginning of the active second stage of labor. Ultrasound parameters are among the significant predictors of duration of the active second stage. Moreover, in fetuses persisting in the OP position vs those delivering in the OA position, fetal head progression seems to differ at early phases of the active second stage.

Safe prevention of the primary cesarean delivery

In 2011, 1 in 3 women who gave birth in the United States did so by cesarean delivery. Cesarean birth can be lifesaving for the fetus, the mother, or both in certain cases. However, the rapid increase in cesarean birth rates from 1996 through 2011 without clear evidence of concomitant decreases in maternal or neonatal morbidity or mortality raises significant concern that cesarean delivery is overused. Variation in the rates of nulliparous, term, singleton, vertex cesarean births also indicates that clinical practice patterns affect the number of cesarean births performed. The most common indications for primary cesarean delivery include, in order of frequency, labor dystocia, abnormal or indeterminate (formerly, nonreassuring) fetal heart rate tracing, fetal malpresentation, multiple gestation, and suspected fetal macrosomia. Safe reduction of the rate of primary cesarean deliveries will require different approaches for each of these, as well as other, indications. For example, it may be necessary to revisit the definition of labor dystocia because recent data show that contemporary labor progresses at a rate substantially slower than what was historically taught. Additionally, improved and standardized fetal heart rate interpretation and management may have an effect. Increasing women's access to nonmedical interventions during labor, such as continuous labor and delivery support, also has been shown to reduce cesarean birth rates. External cephalic version for breech presentation and a trial of labor for women with twin gestations when the first twin is in cephalic presentation are other of several examples of interventions that can contribute to the safe lowering of the primary cesarean delivery rate.

Labor in 2013: the new frontier

Despite the frequency with which obstetrics providers manage labor, evidence has emerged in the past few years challenging our historical understanding of normal labor progress over time. We are also confronted with the dearth of evidence to guide the optimal management of labor. With these data, we are presented with both the challenge of changing practice at the bedside and the opportunity for new discovery to optimize labor and delivery outcomes. Given the sheer frequency of labor and delivery, changes that improve outcomes even by a small magnitude have the potential to dramatically impact labor-associated morbidity at the population level.

Medical and nonmedical factors influencing utilization of delayed pushing in the second stage

OBJECTIVE

To evaluate factors impacting selection to delayed pushing in the second stage of labor.

STUDY DESIGN

This case-control study was a secondary analysis of a large retrospective cohort study. Cases included women who delayed pushing for 60 minutes or more in the second stage of labor. Controls began pushing prior to 60 minutes from the time of diagnosis of complete dilation. Demographic, labor, and nonmedical factors were compared among cases and controls. Logistic regression modeling was used to identify factors independently associated with delayed pushing.

RESULTS

We identified 471 women who delayed pushing and 4819 controls. Nulliparity, maternal body mass index > 25, high fetal station at complete dilation, regional anesthesia use, and start of second stage during staffing shift change were independent factors associated with increased use of delayed pushing. On the other hand, black race and second-stage management during night shift were associated with lower odds of employing delayed pushing. Delayed pushing was more commonly employed in nulliparous women, but 38.9% of multiparous women also delayed pushing.

CONCLUSION

We identified multiple factors associated with use of delayed pushing. This study helps to define current patterns of second-stage labor management.

Immediate compared with delayed pushing in the second stage of labor: a systematic review and meta-analysis

OBJECTIVE

To estimate whether immediate or delayed pushing in the second stage of labor optimizes spontaneous vaginal delivery and other perinatal outcomes.

DATA SOURCES

We searched electronic databases MEDLINE and CINHAL through August 2011 without restrictions. The search terms used were MeSH headings, text words, and word variations of the words or phrases labor, laboring down, passive descent, passive second stage, physiologic second stage, spontaneous pushing, pushing, or bearing down.

METHODS OF STUDY SELECTION

We searched for randomized controlled trials comparing immediate with delayed pushing in the second stage of labor. The primary outcome was spontaneous vaginal delivery. Secondary outcomes were instrumental delivery, cesarean delivery, duration of the second stage, duration of active pushing, and other maternal and neonatal outcomes. Heterogeneity was assessed using the Q test and I2. Pooled relative risks (RRs) and weighted mean differences were calculated using random-effects models.

TABULATION, INTEGRATION, AND RESULTS

Twelve randomized controlled trials (1,584 immediate and 1,531 delayed pushing) met inclusion criteria. Overall, delayed pushing was associated with an increased rate of spontaneous vaginal delivery compared with immediate pushing (61.5% compared with 56.9%, pooled RR 1.09, 95% confidence interval [CI] 1.03-1.15). This increase was smaller and not statistically significant among high-quality studies (59.0% compared with 54.9%, pooled RR 1.07, 95% CI 0.98-1.26) but larger and statistically significant in lower-quality studies (81.0% compared with 71.0%%, pooled RR 1.13, 95% CI 1.02-1.24). Operative vaginal delivery rates were high in most studies and not significantly different between the two groups (33.7% compared with 37.4%, pooled RR 0.89, 95% CI 0.76-1.06). Delayed pushing was associated with prolongation of the second stage (weighted mean difference 56.92 minutes, 95% CI 42.19-71.64) and shortened duration of active pushing (weighted mean difference -21.98 minutes, 95% CI -31.29 to -12.68).

CONCLUSION

Studies to date suggest there are few clinical differences in outcomes with immediate compared with delayed pushing in the second stage of labor, especially when high-quality studies are pooled. Effects on maternal and neonatal outcomes remain uncertain.

How does the duration of active pushing in labor affect neonatal outcomes?

AIM

To assess the effect of time of active pushing (TAP) on neonatal outcome.

MATERIALS AND METHODS

The study population (n=36,432) was taken from a Swedish randomized control trial on intrapartum monitoring, a European Union fetal electrocardiogram trial, and from Mölndal Hospital. After validation of acid-base samples and TAP, 22,812 cases were accepted for analysis.

RESULTS

The median active TAP was 36 min for P0 and 13 min for P≥1 (P<0.001). After adjustments for parity, epidural, labor induction, birth weight, and gender, pushing for 15-29 min (n=6589) relative to pushing for <15 min (n=7264) increased the OR of a cord artery pH of <7.00 to 3.20 (95% CI 1.7-6.0), and that of a base deficit in extracellular fluid of >12 mmol/L to 3.5 (95% CI 1.3-9.0). The group with a cord artery pH of <7.00 had a longer TAP than the group with pH≥7.00: median (5th-95th percentile), 38 (9-107) min vs. 23 (5-87) min, P<0.001. The probability of a spontaneous vaginal delivery decreased significantly with every subsequent increase of 30 min in TAP (P<0.05).

CONCLUSION

The risks of severe acidemia, metabolic acidosis, and deteriorated neonatal outcome gradually increased with the length of TAP (>15 min), while the probability of a spontaneous vaginal delivery decreased with the duration of pushing. We suggest active physiological evaluation of the labor progress together with continuous electronic fetal monitoring during pushing irrespective of guideline thresholds.