Does routine induction of labour at 41 weeks really reduce the rate of caesarean section compared with expectant management?

A cascade of interventions: A classification tree analysis of the determinants of primary cesareans in Australian public hospitals

BACKGROUND

Both globally and in Australia, there has been a sharp rise in cesarean births (CB). Commonly, this rise has been attributed to the changing epidemiology of women giving birth. A significant body of knowledge exists on the risk factors associated with a greater need for cesarean. Yet, we have little information on the reasons recorded by clinicians as to why cesareans are provided. This study aimed to explore the drivers of primary cesareans in Australian public hospitals.

METHODS

Using a linked administrative data set, the frequency and percent of mothers' characteristics were compared between those who had a cesarean birth and those who had a vaginal birth (n = 98 967) with no history of previous cesareans in Queensland public hospitals between July 1, 2012, and June 30, 2015. The top 10 reasons recorded by clinicians for a primary cesarean were reported. Using a machine-learning algorithm, two decision trees were built to determine factors driving primary cesarean birth.

RESULTS

"Labour and delivery complicated by fetal heart rate anomaly" (23%) and "primary inadequate contractions" (22.8%) were the top two reasons for a primary cesarean birth. The most common characteristics among mothers who had fetal heart rate anomalies were as follows: artificial rupture of membranes (39%), oxytocin (32%), no obstruction of labor (42%), and epidural (52%). For women who had primary inadequate contractions, the most common characteristics were as follows: epidural (33%), oxytocin (49%), artificial rupture of membranes (45%), and fetal stress (56%).

CONCLUSIONS

Efforts should be made by health practitioners during the antenatal period to maximize the use of preventative measures that minimize the need for medical interventions.

Induction of labour with unfavourable local conditions for suspected fetal growth restriction after 36 weeks of gestation: Factors associated with the risk of caesarean

INTRODUCTION

Induction of labour in women with an unfavourable cervix is associated with a risk of caesarean delivery. When a diagnosis of fetal growth restriction (FGR) is also involved, the risk of intrapartum fetal acidosis increases. The main objective was to identify prognostic factors for the risk of caesarean delivery after induction for suspected FGR after 36 weeks of gestation with an unripe cervix.

MATERIAL AND METHODS

This was a retrospective, single-centre (Port Royal, Paris, France) study of women with a singleton fetus in cephalic presentation, with labour induced at or after 36 weeks for suspected FGR diagnosed during second or third trimester of pregnancy with an unripe cervix (Bishop score under 6) who gave birth between 1 January 2015 and 31 December 2019. A multivariable analysis was performed to identify the factors related to an increased risk of caesarean section.

RESULTS

Of the 146 women included, 56 (38.4 %) had caesarean deliveries. After adjustment, the factors significantly associated with the risk of caesarean were maternal age greater than 39 years (ORa = 4.33 [1.22-17.2], reference: 25-39 years), nulliparity (ORa = 3.49 [1.25-11.2]), and an abnormal fetal umbilical artery Doppler velocimetry (ORa = 3.50 [1.47-8.70]). The risk of poor neonatal condition did not differ significantly between women with vaginal and caesarean deliveries (2.3 % vs 7.3 %, P = 0.21).

CONCLUSION

When FGR is suspected at 36 weeks of gestation and later, induction of labour is a reasonable option, even if the cervix is unripe, as the risk of caesarean delivery appears acceptable and neonatal status is good and similar with both modes of delivery.

A systematic scoping review of clinical indications for induction of labour

BACKGROUND

The proportion of women undergoing induction of labour (IOL) has risen in recent decades, with significant variation within countries and between hospitals. The aim of this study was to review research supporting indications for IOL and determine which indications are supported by evidence and where knowledge gaps exist.

METHODS

A systematic scoping review of quantitative studies of common indications for IOL. For each indication, we included systematic reviews/meta-analyses, randomised controlled trials (RCTs), cohort studies and case control studies that compared maternal and neonatal outcomes for different modes or timing of birth. Studies were identified via the databases PubMed, Maternity and Infant Care, CINAHL, EMBASE, and ClinicalTrials.gov from between April 2008 and November 2019, and also from reference lists of included studies. We identified 2554 abstracts and reviewed 300 full text articles. The quality of included studies was assessed using the RoB 2.0, the ROBINS-I and the ROBIN tool.

RESULTS

68 studies were included which related to post-term pregnancy (15), hypertension/pre-eclampsia (15), diabetes (9), prelabour rupture of membranes (5), twin pregnancy (5), suspected fetal compromise (4), maternal elevated body mass index (BMI) (4), intrahepatic cholestasis of pregnancy (3), suspected macrosomia (3), fetal gastroschisis (2), maternal age (2), and maternal cardiac disease (1). Available evidence supports IOL for women with post-term pregnancy, although the evidence is weak regarding the timing (41 versus 42 weeks), and for women with hypertension/preeclampsia in terms of improved maternal outcomes. For women with preterm premature rupture of membranes (24-37 weeks), high-quality evidence supports expectant management rather than IOL/early birth. Evidence is weakly supportive for IOL in women with term rupture of membranes. For all other indications, there were conflicting findings and/or insufficient power to provide definitive evidence.

CONCLUSIONS

While for some indications, IOL is clearly recommended, a number of common indications for IOL do not have strong supporting evidence. Overall, few RCTs have evaluated the various indications for IOL. For conditions where clinical equipoise regarding timing of birth may still exist, such as suspected macrosomia and elevated BMI, researchers and funding agencies should prioritise studies of sufficient power that can provide quality evidence to guide care in these situations.

Effects of induction of labor prior to post-term in low-risk pregnancies: a systematic review

OBJECTIVE

The objective of this review was to identify, assess and synthesize the best available evidence on the effects of induction prior to post-term on the mother and fetus. Maternal and fetal outcomes after routine labor induction in low-risk pregnancies at 41+0 to 41+6 gestational weeks (prior to post-term) were compared to routine labor induction at 42+0 to 42+6 gestational weeks (post-term).

INTRODUCTION

Induction of labor when a pregnancy exceeds 14 days past the estimated due date has long been used as an intervention to prevent adverse fetal and maternal outcomes. Over the last decade, clinical procedures have changed in many countries towards earlier induction. A shift towards earlier inductions may lead to 15-20% more inductions. Given the fact that induction as an intervention can cause harm to both mother and child, it is essential to ensure that the benefits of the change in clinical practice outweigh the harms.

INCLUSION CRITERIA

This review included studies with participants with expected low-risk deliveries, where both fetus and mother were considered healthy at inclusion and with no known risks besides the potential risk of the ongoing pregnancy. Included studies evaluated induction at 41+1-6 gestational weeks compared to 42+1-6 gestational weeks. Randomized control trials (n = 2), quasi-experimental trials (n = 2), and cohort studies (n = 3) were included. The primary outcomes of interest were cesarean section, instrumental vaginal delivery, low Apgar score (≤ 7/5 min.), and low pH (< 7.10). Secondary outcomes included additional indicators of fetal or maternal wellbeing related to prolonged pregnancy or induction.

METHODS

The following information sources were searched for published and unpublished studies: PubMed, CINAHL, Embase, Scopus, Swemed+, POPLINE; Cochrane, TRIP; Current Controlled Trials; Web of Science, and, for gray literature: MedNar; Google Scholar, ProQuest Nursing & Allied Health Source, and guidelines from the Royal College of Obstetricians and Gynaecologists, and American College of Obstetricians and Gynecologists, according to the published protocol. In addition, OpenGrey and guidelines from the National Institute for Health and Care Excellence, World Health Organization, and Society of Obstetricians and Gynaecologists of Canada were sought. Included papers were assessed by all three reviewers independently using the Joanna Briggs Institute System for the Unified Management, Assessment and Review of Information (JBI SUMARI). The standardized data extraction tool from JBI SUMARI was used. Data were pooled in a statistical meta-analysis model using RevMan 5, when the criteria for meta-analysis were met. Non-pooled results were presented separately.

RESULTS

Induction at 41+0-6 gestational weeks compared to 42+0-6 gestational weeks was found to be associated with an increased risk of overall cesarean section (relative risk [RR] = 1.11, 95% confidence interval [CI] 1.09-1.14), cesarean section due to failure to progress (RR = 1.43, 95% CI 1.01-2.01), chorioamnionitis (RR = 1.13, 95% CI 1.05-1.21), labor dystocia (RR = 1.29, 95% CI 1.22-1.37), precipitate labor (RR = 2.75, 95% CI 1.45-5.2), uterine rupture (RR = 1.97, 95% CI 1.54-2.52), pH < 7.10 (RR = 1.9, 95% CI 1.48-2.43), and a decreased risk of oligohydramnios (RR = 0.4, 95% CI 0.24-0.67) and meconium stained amniotic fluid (RR = 0.82, 95% CI 0.75-0.91). Data lacked statistical power to draw conclusions on perinatal death. No differences were seen for postpartum hemorrhage, shoulder dystocia, meconium aspiration, 5-minute Apgar score < 7, or admission to neonatal intensive care unit. A policy of awaiting spontaneous onset of labor until 42+0-6 gestational weeks showed, that approximately 70% went into spontaneous labor.

CONCLUSIONS

Induction prior to post-term was associated with few beneficial outcomes and several adverse outcomes. This draws attention to possible iatrogenic effects affecting large numbers of low-risk women in contemporary maternity care. According to the World Health Organization, expected benefits from a medical intervention must outweigh potential harms. Hence, our results do not support the widespread use of routine induction prior to post-term (41+0-6 gestational weeks).

Induction at 41 weeks increases the risk of caesarean section in a hospital with a low rate of caesarean sections

OBJECTIVE

To analyse the impact of a change in the management of prolonged pregnancies from inducing labour at 42(+0) to induction at 41(0-6).

DESIGN

Retrospective cohort study.

METHODS

Analysis of 3563 single pregnancies with cephalic presentation of ≥ 41 weeks of gestation delivered in Cruces University Hospital (Spain). Two cohorts were compared corresponding to before and after the change in the policy on induction.

MAIN OUTCOME MEASURES

Induction rate, vaginal delivery rate, newborn morbidity and mortality.

RESULTS

The overall rate of caesarean sections in the patients included in the study was 12.8% (19.5% among those induced and 8.4% among those in whom the onset of labour has been spontaneous). The caesarean section rate in cohorts 41(0-6) and 42(+0) were 14.1% and 11.4%, respectively (p=0.01). Though there were more newborns with umbilical cord blood ph<7.10 in cohort 41(0-6) than in the other group (8.7% versus 4.5%; p<0.01), no significant differences were found between cohorts in 5-min Apgar score < 7, number of admissions to the neonatal care unit or perinatal mortality.

CONCLUSION

The induction of labour during week 41 in prolonged pregnancies may increase the rate of caesarean sections in hospitals with low rates of caesarean sections.