Induction of Labour at Term With Oral Misoprostol Versus a Foley Catheter (PROBAAT-II)

Abstract

When pregnancy complications pose a threat to the mother or fetus or both, induction of labor is often required. Induction of labor is accomplished through a variety of methods; in pregnant women having an unfavourable cervix, cervical ripening of the cervix is accomplished through various mechanical and pharmacological means. Oral misoprostol and Foley catheter are believed to be equally effective in women with an unfavorable cervix in accomplishing vaginal birth. The current open-label randomized noninferiority trial was conducted in pregnant women with a singleton gestation in 29 hospitals in the Netherlands (2012 to 2013) to directly compare oral misoprostol with Foley catheter. Women with a viable singleton pregnancy in cephalic presentation, intact membranes, gestational age of 37 weeks or more, and an unfavorable cervix were included in the trial. The women were then randomly allocated (1:1) to oral misoprostol (n = 932) or Foley catheter (n = 927). Oral misoprostol dosage given was 50 µg orally once every 4 hours with a maximum of 3 times a day. Placement of a 30-mL Foley catheter in the cervix was done either digitally or using a vaginal speculum. The results of the study showed that the primary outcome (asphyxia or postpartum hemorrhage) occurred in 12.2% women in the misoprostol group and in 11.5% women in the Foley catheter group (adjusted relative risk [RR], 1.06; 90% confidence interval [CI], 0.86–1.31). Cesarean delivery resulted in 16.8% of labors in the misoprostol group and in 20.1% of the time in the Foley catheter group (no significant difference between groups [RR, 0.84; 95% CI, 0.69–1.01]). When the indication for cesarean delivery was examined, fewer cesarean deliveries for failure to progress in the first stage occurred after induction in the misoprostol group than in the Foley catheter group (6.2% vs 10.6%; RR, 0.58; 95% CI, 0.42–0.79). In addition, operative vaginal delivery occurred more frequently in the misoprostol group. Among the misoprostol group spontaneous membrane rupture was more common and labor augmentation with oxytocin was less likely. The study leads to a conclusion that in terms of safety and effectiveness, induction of labour using oral misoprostol is as safe as mechanical induction using Foley catheter.