Induction of labour at term with oral misoprostol versus a Foley catheter (PROBAAT-II): a multicentre randomised controlled non-inferiority trial

Background Labour is induced in 20-30% of all pregnancies. In women with an unfavourable cervix, both oral misoprostol and Foley catheter are equally effective compared with dinoprostone in establishing vaginal birth, but each has a better safety profile. We did a trial to directly compare oral misoprostol with Foley catheter alone. Methods We did an open-label randomised non-inferiority trial in 29 hospitals in the Netherlands. Women with a term singleton pregnancy in cephalic presentation, an unfavourable cervix, intact membranes, and without a previous caesarean section who were scheduled for induction of labour were randomly allocated to cervical ripening with 50 mu g oral misoprostol once every 4 h or to a 30 mL transcervical Foley catheter. The primary outcome was a composite of asphyxia (pH <= 7.05 or 5-min Apgar score <7) or post-partum haemorrhage (>= 1000 mL). The non-inferiority margin was 5%. The trial is registered with the Netherlands Trial Register, NTR3466. Findings Between July, 2012, and October, 2013, we randomly assigned 932 women to oral misoprostol and 927 women to Foley catheter. The composite primary outcome occurred in 113 (12.2%) of 924 participants in the misoprostol group versus 106 (11.5%) of 921 in the Foley catheter group (adjusted relative risk 1.06, 90% CI 0.86-1.31). Caesarean section occurred in 155 (16.8%) women versus 185 (20.1%; relative risk 0.84, 95% CI 0.69-1.02, p=0.067). 27 adverse events were reported in the misoprostol group versus 25 in the Foley catheter group. None were directly related to the study procedure. Interpretation In women with an unfavourable cervix at term, induction of labour with oral misoprostol and Foley catheter has similar safety and effectiveness.