Comparing expectant management and spontaneous labor approaches in studying the effect of labor induction on cesarean delivery

Term Labor Induction and Cesarean Delivery Risk among Obese Women with and without Comorbidities

OBJECTIVE

Findings of the recent ARRIVE (A Randomized Trial of Induction Versus Expectant Management) trial, showing reduced cesarean risk with elective labor induction among low-risk nulliparous women at 39 weeks' gestation, have the potential to change interventional delivery practices but require examination in wider populations. The aim of this study was to identify whether term induction of labor was associated with reduced cesarean delivery risk among women with obesity, evaluating several maternal characteristics associated with obesity, induction, and cesarean risk.

STUDY DESIGN

We studied administrative records for 66,280 singleton, term births to women with a body mass index ≥30, without a prior cesarean delivery, in New York City from 2008 to 2013. We examined elective inductions in 39 and 40 weeks' gestation and calculated adjusted risk ratios for cesarean delivery risk, stratified by parity and maternal age. We additionally evaluated medically indicated inductions at 37 to 40 weeks among women with obesity and diabetic or hypertensive disorders, comorbidities that are strongly associated with obesity.

RESULTS

Elective induction of labor was associated with a 25% (95% confidence interval: 19-30%) lower adjusted risk of cesarean delivery as compared with expectant management at 39 weeks of gestation and no change in risk at 40 weeks. Patterns were similar when stratified by parity and maternal age. Risk reductions in week 39 were largest among women with a prior vaginal delivery. Women with comorbidities had reduced cesarean risk with early term induction and in 39 weeks.

CONCLUSION

Labor induction at 39 weeks was consistently associated with reduced risk of cesarean delivery among women with obesity regardless of parity, age, or comorbidity status. Cesarean delivery findings from induction trials at 39 weeks among low-risk nulliparous women may generalize more broadly across the U.S. obstetric population, with potentially larger benefit among women with a prior vaginal delivery.

KEY POINTS

· We found reduced cesarean risk with induction at 39 weeks.. · Results were consistent for age and comorbidity subgroups.. · Risk reductions were largest among multiparous women..

Delivery at 39 Weeks of Gestation: The Time Has Come

It has long been observed that neonates born between 39 and 40 gestational weeks have the best perinatal outcomes. What has not been known, until recently, is whether these ideal perinatal outcomes would be achieved in neonates whose delivery was brought on intentionally in this window by labor induction. Recent randomized trials and large observational cohorts have answered this question: labor induction, as compared with expectant management, lowers the rate of cesarean delivery (without increasing other adverse maternal outcomes) and improves perinatal outcomes. For those women still pregnant, delivery at 39 weeks of gestation would simultaneously lower the number of cesarean deliveries and reduce the number of stillbirths and neonatal deaths in the United States.

Induction of labour at or beyond 37 weeks' gestation

BACKGROUND

Risks of stillbirth or neonatal death increase as gestation continues beyond term (around 40 weeks' gestation). It is unclear whether a policy of labour induction can reduce these risks. This Cochrane Review is an update of a review that was originally published in 2006 and subsequently updated in 2012 and 2018.

OBJECTIVES

To assess the effects of a policy of labour induction at or beyond 37 weeks' gestation compared with a policy of awaiting spontaneous labour indefinitely (or until a later gestational age, or until a maternal or fetal indication for induction of labour arises) on pregnancy outcomes for the infant and the mother.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (17 July 2019), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) conducted in pregnant women at or beyond 37 weeks, comparing a policy of labour induction with a policy of awaiting spontaneous onset of labour (expectant management). We also included trials published in abstract form only. Cluster-RCTs, quasi-RCTs and trials using a cross-over design were not eligible for inclusion in this review. We included pregnant women at or beyond 37 weeks' gestation. Since risk factors at this stage of pregnancy would normally require intervention, only trials including women at low risk for complications, as defined by trialists, were eligible. The trials of induction of labour in women with prelabour rupture of membranes at or beyond term were not considered in this review but are considered in a separate Cochrane Review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, assessed risk of bias and extracted data. Data were checked for accuracy. We assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

In this updated review, we included 34 RCTs (reporting on over 21,000 women and infants) mostly conducted in high-income settings. The trials compared a policy to induce labour usually after 41 completed weeks of gestation (> 287 days) with waiting for labour to start and/or waiting for a period before inducing labour. The trials were generally at low to moderate risk of bias. Compared with a policy of expectant management, a policy of labour induction was associated with fewer (all-cause) perinatal deaths (risk ratio (RR) 0.31, 95% confidence interval (CI) 0.15 to 0.64; 22 trials, 18,795 infants; high-certainty evidence). There were four perinatal deaths in the labour induction policy group compared with 25 perinatal deaths in the expectant management group. The number needed to treat for an additional beneficial outcome (NNTB) with induction of labour, in order to prevent one perinatal death, was 544 (95% CI 441 to 1042). There were also fewer stillbirths in the induction group (RR 0.30, 95% CI 0.12 to 0.75; 22 trials, 18,795 infants; high-certainty evidence); two in the induction policy group and 16 in the expectant management group. For women in the policy of induction arms of trials, there were probably fewer caesarean sections compared with expectant management (RR 0.90, 95% CI 0.85 to 0.95; 31 trials, 21,030 women; moderate-certainty evidence); and probably little or no difference in operative vaginal births with induction (RR 1.03, 95% CI 0.96 to 1.10; 22 trials, 18,584 women; moderate-certainty evidence). Induction may make little or difference to perineal trauma (severe perineal tear: RR 1.04, 95% CI 0.85 to 1.26; 5 trials; 11,589 women; low-certainty evidence). Induction probably makes little or no difference to postpartum haemorrhage (RR 1.02, 95% CI 0.91 to 1.15, 9 trials; 12,609 women; moderate-certainty evidence), or breastfeeding at discharge (RR 1.00, 95% CI 0.96 to 1.04; 2 trials, 7487 women; moderate-certainty evidence). Very low certainty evidence means that we are uncertain about the effect of induction or expectant management on the length of maternal hospital stay (average mean difference (MD) -0.19 days, 95% CI -0.56 to 0.18; 7 trials; 4120 women; Tau² = 0.20; I² = 94%). Rates of neonatal intensive care unit (NICU) admission were lower (RR 0.88, 95% CI 0.80 to 0.96; 17 trials, 17,826 infants; high-certainty evidence), and probably fewer babies had Apgar scores less than seven at five minutes in the induction groups compared with expectant management (RR 0.73, 95% CI 0.56 to 0.96; 20 trials, 18,345 infants; moderate-certainty evidence). Induction or expectant management may make little or no difference for neonatal encephalopathy (RR 0.69, 95% CI 0.37 to 1.31; 2 trials, 8851 infants; low-certainty evidence, and probably makes little or no difference for neonatal trauma (RR 0.97, 95% CI 0.63 to 1.49; 5 trials, 13,106 infants; moderate-certainty evidence) for induction compared with expectant management. Neurodevelopment at childhood follow-up and postnatal depression were not reported by any trials. In subgroup analyses, no differences were seen for timing of induction (< 40 versus 40-41 versus > 41 weeks' gestation), by parity (primiparous versus multiparous) or state of cervix for any of the main outcomes (perinatal death, stillbirth, NICU admission, caesarean section, operative vaginal birth, or perineal trauma).

AUTHORS' CONCLUSIONS

There is a clear reduction in perinatal death with a policy of labour induction at or beyond 37 weeks compared with expectant management, though absolute rates are small (0.4 versus 3 deaths per 1000). There were also lower caesarean rates without increasing rates of operative vaginal births and there were fewer NICU admissions with a policy of induction. Most of the important outcomes assessed using GRADE had high- or moderate-certainty ratings. While existing trials have not yet reported on childhood neurodevelopment, this is an important area for future research. The optimal timing of offering induction of labour to women at or beyond 37 weeks' gestation needs further investigation, as does further exploration of risk profiles of women and their values and preferences. Offering women tailored counselling may help them make an informed choice between induction of labour for pregnancies, particularly those continuing beyond 41 weeks - or waiting for labour to start and/or waiting before inducing labour.

Elucidating the role of overweight and obesity in racial and ethnic disparities in cesarean delivery risk

PURPOSE

We aimed to quantify the extent to which overweight and obesity explain cesarean delivery risk among women of different racial and ethnic backgrounds.

METHODS

Using administrative records for 216,481 singleton, nulliparous births in New York City from 2008 to 2013, we calculated risk ratios, risk differences, and population attributable fractions for associations between body mass index (BMI) and cesarean, stratified by race and ethnicity.

RESULTS

The population attributable fraction (95% confidence interval) for BMI was 6.8% (6.2%-7.3%) among Asian, 10.9% (10.4%-11.4%) among White, 14.6% (13.7%-15.5%) among Hispanic, and 17.4% (16.2%-18.6%) among Black women. Although overweight and obesity were most prevalent among Black and Hispanic women, the risk gradient was strongest among Whites (adjusted risk ratio [95% CI] from 1.37 [1.33-1.41] for overweight to 2.23 [2.07-2.39] for class III obesity). Additional adjustment for gestational complications partially attenuated associations, and accounting for delivery hospital eliminated the stronger gradient among White women.

CONCLUSIONS

Prepregnancy overweight and obesity contribute proportionally more to cesarean risk among Black and Hispanic women because of higher prevalence compared to White or Asian women. Although preconception weight management is important to decrease cesarean risk, results encourage attention to clinical approaches in low-risk pregnancies to mitigate racial and ethnic perinatal disparities.

Elective induction of labor at 39 weeks compared with expectant management: a meta-analysis of cohort studies

BACKGROUND

Elective induction of labor at 39 weeks among low-risk nulliparous women has reduced the chance of cesarean and other adverse maternal and perinatal outcomes in a randomized trial, although its clinical effectiveness in nonresearch settings remains uncertain.

OBJECTIVE

To perform a systematic review of observational studies that compared elective induction of labor at 39 weeks among nulliparous women with expectant management and to use meta-analytic techniques to estimate the association of elective induction with cesarean delivery, as well as other maternal and perinatal outcomes.

STUDY DESIGN

Studies were eligible for this meta-analysis only if they: (1) were observational; (2) compared women undergoing labor induction at 39 weeks with women undergoing expectant management beyond that gestational age; (3) included women in the induction group only if they had no other indication for labor induction at 39 weeks; and (4) provided data specifically for nulliparous women. The predefined primary outcome was cesarean delivery, and secondary outcomes representing other maternal and perinatal morbidities also were evaluated. Outcome data from different studies were combined to estimate pooled relative risks with 95% confidence intervals using random-effects models.

RESULTS

Of 375 studies identified by the initial search, 6 cohort studies, which included 66,019 women undergoing elective labor induction at 39 weeks and 584,390 undergoing expectant management, met inclusion criteria. Elective induction of labor at 39 weeks was associated with a significantly lower frequency of cesarean delivery (26.4% vs 29.1%; relative risk, 0.83; 95% confidence interval, 0.74-0.93), as well as of peripartum infection (2.8% vs 5.2%; relative risk, 0.53; 95% confidence interval, 0.39-0.72). Neonates of women in the induction group were less likely to have respiratory morbidity (0.7% vs 1.5%; relative risk, 0.71; 95% confidence interval, 0.59-0.85); meconium aspiration syndrome (0.7% vs 3.0%; relative risk, 0.49; 95% confidence interval, 0.26-0.92); and neonatal intensive care unit admission (3.5% vs 5.5%; relative risk, 0.80; 95% confidence interval, 0.72-0.88). There also was a lower risk of perinatal mortality (0.04% vs 0.2%; relative risk, 0.27; 95% confidence interval, 0.09-0.76).

CONCLUSION

This meta-analysis of 6 cohort studies demonstrates that elective induction of labor at 39 weeks, compared with expectant management beyond that gestational age, was associated with a significantly lower risk of cesarean delivery, maternal peripartum infection, and perinatal adverse outcomes, including respiratory morbidity, intensive care unit admission, and mortality.

Predictors for cesarean delivery in preterm premature rupture of membranes

Objective: To determine predictors for cesarean delivery (CD) in pregnancies complicated by preterm premature rupture of membranes (PPROM) with an intention for vaginal delivery.Materials and methods: A retrospective cohort analysis of all singleton, preterm deliveries (24 + 0 to 36 + 6 weeks) following PPROM (2007-2014). Exclusion criteria included: cases intended for CD prior to delivery; short interval from PPROM to delivery (<24 hours); cervical dilatation upon admission ≥4 cm; and major fetal anatomical/chromosomal abnormalities. Potential CD predictors were evaluated by univariate followed by multivariate regression analysis.Results: Overall, 465 deliveries met inclusion criteria. Of them, 53 (11.4%) ended with CD. Women in the CD group delivered at an earlier gestational age (34 versus 35 weeks) with lower birth weights (2115 versus 2386 grams), p < .05 for both. On univariate analysis, smaller cervical dilatation upon admission and prior to delivery, longer PPROM to delivery interval and delivery indication were the only significant determinants associated CD (p < .001 for all). On multivariable regression analysis, only la rger cervical dilatation prior to delivery remained an independent factor for lower rates of CD (aOR 0.15, 95% CI 0.08-0.28, p < .001).Conclusion: Small cervical dilatation prior to delivery is an independent risk factor for CD in pregnancies complicated by PPROM.

Labor Induction with Orally Administrated Misoprostol: A Retrospective Cohort Study

Introduction

One great challenge in obstetric care is labor inductions. Misoprostol has advantages in being cheap and stable at room temperature and available in resource-poor settings.

Material and Methods

Retrospective cohort study of 4002 singleton pregnancies with a gestational age ≥34 w at Sodersjukhuset, Stockholm, during 2009-2010 and 2012-2013. Previously used methods of labor induction were compared with misoprostol given as a solution to drink, every second hour. Main outcome is as follows: Cesarean Section (CS) rate, acid-base status in cord blood, Apgar score < 7,5′, active time of labor, and blood loss > 1500 ml (PPH).

Results

The proportion of CS decreased from 26% to 17% when orally given solution of misoprostol was introduced at the clinic (p < 0.001). No significant difference in the frequency of low Apgar score (p = 0.3), low aPh in cord blood (p = 0.1), or PPH (p = 0.4) between the different methods of induction was studied. After adjustment for different risk factor for CS the only method of induction which was associated with CS was dinoproston^⁎⁎ (Propess®) (aor = 2.9 (1.6–5.2)).

Conclusion

Induction of labor with misoprostol, given as an oral solution to drink every second hour, gives a low rate of CS, without affecting maternal or fetal outcome.

Does a policy of earlier induction affect labour outcomes in women induced for postmaturity? A retrospective analysis in a tertiary hospital in the North of England

OBJECTIVES

to investigate whether a change in the management of postmature pregnancy to earlier induction affects the length of labour and the induction process. Secondly, to assess the feasibility of the research process to inform a future larger study.

DESIGN

a change in management of postmature pregnancy in an NHS hospital in October 2013, from induction at 42 weeks gestation to induction between 41-42 weeks, provided an opportunity to conduct a retrospective analysis. Pre-existing data from the maternity database and casenotes were collected and primary outcomes analysed using the Mann-Whitney test and the Hodges-Lehman confidence interval for differences in medians.

SETTING

a large city based tertiary referral hospital in the North of England.

PARTICIPANTS

125 women induced before the change in policy were compared with 309 women induced after the change.

MEASUREMENTS

primary outcomes were length of 1st and 2nd stage of labour, overall length of labour, length of induction to established labour and length of induction to birth.

FINDINGS

the median overall length of labour for women induced at 42 weeks was 6.5hours, while for women induced at 41-42 weeks this was 5.2hours. The difference was not statistically significant (p=0.15, 95% CI for median difference -0.27 to 1.93hours) with a small effect size (Pearson's r=-0.08). The median length of induction to birth was 13.6hours for women induced at 42 weeks and 16.5hours for women induced at 41-42 weeks. This difference was also not statistically significant (p=0.14, 95% CI for median difference -7.25 to 1.20hours) with a small effect size (Pearson's r=-0.13).

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

This study demonstrated no statistically significant differences in length of labour and induction following a change in the management of postmature pregnancy to earlier induction. A large study is needed to establish definitively the effects of earlier induction on labour outcomes.

Intrapartum intervention rates and perinatal outcomes following induction of labour compared to expectant management at term from an Australian perinatal centre

BACKGROUND

Induction of labor (IOL) is a common obstetric intervention, yet its impact on intervention rates and perinatal outcomes is conflicting.

AIMS

To evaluate the impact of IOL on intrapartum intervention rates and perinatal outcomes in women with singleton pregnancies at term.

MATERIAL AND METHODS

This was a retrospective, cross-sectional study of term singleton deliveries at the Mater Mother's Hospital in Brisbane, Australia in 2007-2013. The IOL cohort was compared to an expectantly managed group.

RESULTS

Of the final cohort (44 698 women), 64.4% had expectant management and 35.6% had IOL. Multivariate analyses showed that IOL was associated with lower odds of spontaneous vaginal delivery from ≥37 weeks gestation. The risk of emergency caesarean for non-reassuring fetal status was also higher in the IOL cohort at 40 and 41 weeks gestation. For women who were managed expectantly, the highest rate of spontaneous vaginal delivery and the lowest rate of emergency caesareans occurred at 39 weeks gestation. For women who underwent IOL, the nadir emergency caesarean rate and the highest spontaneous vaginal delivery rate was also at 39 weeks. Rates of neonatal intensive car unit admission were higher in the IOL group at 37 weeks (adjusted odds ratio (aOR) 3.11, 95% CI: 2.62-3.68) and 38 weeks (aOR 1.78, 95% CI: 1.55-2.04) and lower at >42 weeks (OR 0.35, 95% CI: 0.14-0.81) respectively.

CONCLUSION

IOL compared to expectant management is associated with lower spontaneous vaginal delivery rates and increased risk of emergency caesarean for intrapartum fetal compromise with broadly comparable perinatal outcomes.