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

Abstract

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 μg 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.

Funding: FondsNutsOhra.