Elective induction of labour in low risk nulliparous women at term: Caution is needed

Randomized controlled trials: not always the "gold standard" for evidence in obstetrics and gynecology

Randomized controlled trials are considered the "gold standard" for therapeutic interventions, and it is not uncommon for sweeping changes in medical practice to follow positive results from such trials. However, randomized controlled trials are not without their limitations. Physicians frequently view randomized controlled trials as infallible, whereas they tend to dismiss evidence derived from sources other than randomized controlled trials as less credible or reliable. In several situations in obstetrics and gynecology, there are no randomized controlled trials to help guide the clinician. In these circumstances, it is important to evaluate the entire body of evidence including observational studies, rather than dismiss interventions altogether simply because no randomized controlled trials exist. Randomized controlled trials and observational studies should be viewed as complementary rather than at odds with each other. Some reversals in widely adopted clinical practice have recently been implemented following subsequent studies that contradicted the outcomes of major randomized controlled trials. The most notable of these was the withdrawal from the market of 17-hydroxyprogesterone caproate for preterm birth prevention. Such reversals could potentially have been averted if the inherent limitations of randomized controlled trials were carefully considered before implementing these universal practice changes. This Clinical Opinion underscores the limitations of an exclusive reliance on randomized controlled trials while disregarding other evidence in determining how best to care for patients. Solutions are proposed that advocate that clinicians adopt a more balanced perspective that considers the entirety of the available medical evidence and the individual patient characteristics, needs, and wishes.

The role of labor induction in modern obstetrics

A primary goal of obstetrical practice is the optimization of maternal and perinatal health. This goal translates into a seemingly simple assessment with regard to considerations of the timing of delivery: delivery should occur when the benefits are greater than those of continued pregnancy. In the absence of an indication for cesarean delivery, planned delivery is initiated with induction of labor. When medical or obstetrical complications exist, they may guide recommendations regarding the timing of delivery. In the absence of these complications, gestational age also has been used to guide delivery timing, given its association with both maternal and perinatal adverse outcomes. If there is no medical indication, delivery before 39 weeks has been discouraged, given its association with greater chances of adverse perinatal outcomes. Conversely, it has been recommended that delivery occur by 42 weeks of gestation, given the perinatal risks that accrue in the post-term period. Historically, a 39-week induction of labor, particularly for individuals with no previous birth, has not been routinely offered in the absence of medical or obstetrical indications. That approach was based on numerous observational studies that demonstrated an increased risk of cesarean delivery and other adverse outcomes among individuals who underwent labor induction compared to those in spontaneous labor. However, from a management and person-centered-choice perspective, the relevant comparison is between those undergoing planned labor induction at a given time vs those planning to continue pregnancy beyond that time. When individuals have been compared using that rubric-either in observational studies or randomized trials that have been performed in a wide variety of locations and populations- there has not been evidence that induction increases adverse perinatal or maternal outcomes. Conversely, even when the only indication for delivery is the achievement of a full-term gestational age, evidence suggests that multiple different outcomes, including cesarean delivery, hypertensive disorders of pregnancy, neonatal respiratory impairment, and perinatal mortality, are less likely when induction is performed. This information underscores the importance of making the preferences of pregnant individuals for different birth processes and outcomes central to the approach to delivery timing.

Induction of labour in low-resource settings

Due to the disparity in resource availability between low- and high-resource settings, practice recommendations relevant to high-income countries are not always relevant and often need to be adapted to low-resource settings. The adaptation applies to induction of labour (IOL) which is an obstetric procedure that deserves special attention because it involves the initiation of a process that requires regular and frequent monitoring of the mother and foetus by experienced healthcare professionals. Lack of problem recognition and/or substandard care during IOL may result in harm with long-term sequelae. In this article, the authors discuss unique challenges such as insufficient resources (including staff, midwives, doctors, equipment, and medications) that result in occasional inadequate patient monitoring and/or delayed interventions during IOL in low-resource settings. We also discuss modifications in indications and methods for IOL, issues related to human immunodeficiency virus (HIV) infections, the feasibility of outpatient induction, clinical protocols and a minimum dataset for quality improvement projects. Overall, the desire to achieve a vaginal birth with IOL should not cloud the necessity to observe the required safety measures and implement necessary interventions; given that childbirth practices are the major determinants of pregnancy outcomes and patient satisfaction.

An hypothetical external validation of the ARRIVE trial in a European academic hospital

BACKGROUND

Recent evidence supports elective induction of labor at 39 weeks in low-risk pregnancies to improve maternal and perinatal outcomes. This evidence includes the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management). However, concerns have been raised on the external validity of the ARRIVE trial, especially with regard to the demographic and clinical characteristics of the pregnant women recruited.

OBJECTIVE

This study compared the outcomes in a cohort of consecutive pregnant women, who fulfilled the criteria of the ARRIVE trial and were managed expectantly in an Italian referral academic hospital, with those reported in the expectant and induction arms of the ARRIVE trial.

STUDY DESIGN

This was a retrospective single-center study. Consecutive low-risk nulliparous women who fulfilled the ARRIVE trial criteria were evaluated for eligibility at 36-38 weeks of gestation. Those who neither developed complications nor delivered spontaneously before 39 weeks were eligible for this comparative analysis. Maternal and fetal growth and wellbeing were screened and monitored from 36 to 38 weeks of gestation.

RESULTS

A total of 1696 patients met the established criteria at recruitment. Of these, 343 spontaneously delivered in <39 weeks, 82 delivered because of maternal indication, and 37 for fetal indication. A total of 1234 pregnant women were eligible for comparison with the elective induction and the expectant management groups of the ARRIVE trial. The socioeconomic status was significantly better, maternal age was significantly higher, and body mass index was significantly lower in our cohort. Cesarean section rate in our cohort was lower than that of the expectant group of the ARRIVE trial (18.7 vs. 22.2%; p = 0.02) and similar to that of the elective induction group (18.7 vs. 18.6%). A new diagnosis of hypertensive disorders during expectant management was noted in 1.6% in our cohort vs. 14.1% in the ARRIVE arm. Among the different obstetric outcomes, only the prevalence of postpartum hemorrhage was not significantly lower in our cohort. The primary perinatal composite outcome was significantly better in our cohort than in both arms of the ARRIVE trial (2.1 vs. 5.4% in the expectant group and 4.3% in the induction group). We did not record cases with an Apgar score ≤ 3 or hypoxic-ischemic encephalopathy.

CONCLUSION

In our cohort, expectant management in low-risk pregnancies with late preterm screening of feto-maternal well-being seemed to achieve better maternal and perinatal outcomes than a universal policy of induction at 39 weeks. The results of the ARRIVE trial should be carefully evaluated in different demographic and clinical settings and cannot be extended to the general population.

Maternal perceptions of the experience of attempted labor induction and medically elective inductions: analysis of survey results from listening to mothers in California

BACKGROUND

The rate of induction of labor in the U.S. has risen from 9.6% in 1990 to 25.7% in 2018, including 31.7% of first-time births. Recent studies that have examined inductions have been small qualitative studies or relied on either medical records or administrative data. This study examines induction from the perspective of those women who experienced it, with a particular focus on the prevalence and predictors of inductions for nonmedical indications, women's experience of pressure to induce labor and the relationship between the attempt to medically initiate labor and cesarean section.

METHODS

Study data are drawn from the 2119 respondents to the Listening to Mothers in California survey who were planning to have a vaginal birth in 2016. Mothers were asked if there had been an attempt to medically initiate labor, if it actually started labor, if they felt pressured to have the induction, if they had a cesarean and the reason for the induction. Reasons for induction were classified as either medically indicated or elective.

RESULTS

Almost half (47%) of our respondents indicated an attempt was made to medically induce their labor, and 71% of those attempts initiated labor. More than a third of the attempts (37%) were elective. Attempted induction overall was most strongly associated with giving birth at 41+ weeks (aOR 3.28; 95% C.I. 2.21-4.87). Elective inductions were more likely among multiparous mothers and in pregnancies at 39 or 40 weeks. The perception of being pressured to have labor induced was related to higher levels of education, maternal preference for less medical intervention in birth, having an obstetrician compared to a midwife and gestational ages of 41+ weeks. Cesarean birth was more likely in the case of overall induction (aOR 1.51; 95% C.I. 1.11-2.07) and especially following a failed attempt at labor induction (aOR 4.50; 95% C.I. 2.93-6.90).

CONCLUSION

Clinicians counselling mothers concerning the need for labor induction should be aware of mothers' perceptions about birth and engage in true shared decision making in order to avoid the maternal perception of being pressured into labor induction.

Induction of labor and nulliparity: A nationwide clinical practice pilot evaluation

INTRODUCTION

Induction of labor has become an increasingly common obstetric procedure, but in nulliparous women or women with a previous cesarean section, it can pose a clinical challenge. Despite an overall expansion of medical indications for labor induction, there is little international consensus regarding the criteria for induction, or for the recommended methods among nulliparous women. In this light, we assessed variations in the practice of induction of labor among 21 birth units in a nationwide cohort of women with no prior vaginal birth.

MATERIAL AND METHODS

We carried out a prospective observational pilot study of women with induced labor and no prior vaginal birth, across 21 Norwegian birth units. We registered induction indications, methods and outcomes from 1 September to 31 December 2018 using a web-based case record form. Women were grouped into "Nulliparous term cephalic", "Previous cesarean section" and "Other Robson" (Robson groups 6, 7, 8 or 10).

RESULTS

More than 98% of eligible women (n=1818) were included and a wide variety of methods was used for induction of labor. In nulliparous term cephalic pregnancies, cesarean section rates ranged from 11.1% to 40.6% between birth units, whereas in the previous cesarean section group, rates ranged from 22.7% to 67.5%. The indications "large fetus" and "other fetal" indications were associated with the highest cesarean rates. Failed inductions and failure to progress in labor contributed most to the cesarean rates. Uterine rupture occurred in two women (0.11%), both in the previous cesarean section group. In neonates, 1.6% had Apgar <7 at 5 minutes, and 0.4% had an umbilical artery pH <7.00.

CONCLUSIONS

Cesarean rates and applied methods for induction of labor varied widely in this nationwide cohort of women without a prior vaginal birth. Neonatal outcomes were similar to those of normal birth populations. Results could indicate the need to move towards more standardized induction protocols associated with optimal outcomes for mother and baby.