Oxytocin versus prostaglandins for labour Induction of women with an unfavourable cervix after 24 hours of cervical ripening (OPIC): protocol for an open multicentre randomised non-inferiority trial

INTRODUCTION: It remains uncertain whether the most appropriate management for women with an unfavourable cervix after 24 hours of cervical ripening is repeating the ripening procedure or proceeding directly to induction by oxytocin. No adequately powered trial has compared these strategies. We hypothesise that induction of labour with oxytocin among women who have just undergone an ineffective first ripening procedure is not associated with a higher risk of caesarean delivery than a repeated cervical ripening with prostaglandins. METHODS AND ANALYSIS: We will conduct a multicentre, non-inferiority, open-label, randomised controlled trial aimed at comparing labour induction by oxytocin with a second cervical ripening that uses prostaglandins (slow-release vaginal dinoprostone; oral misoprostol 25 µg; dinoprostone vaginal gel 2 mg). Women (n=1494) randomised in a 1:1 ratio in 10 French maternity units must be ≥18 years with a singleton fetus in vertex presentation, at a term from ≥37+0 weeks of gestation, and have just completed a 24-hour cervical ripening procedure by any method (pharmacological or mechanical) with a Bishop score ≤6. Exclusion criteria comprise being in labour, having more than 3 contractions per 10 min, or a prior caesarean delivery or a history of uterine surgery, or a fetus with antenatally suspected severe congenital abnormalities or a non-reassuring fetal heart rate. The primary endpoint will be the caesarean delivery rate, regardless of indication. Secondary outcomes concern delivery, perinatal morbidity, maternal satisfaction and health economic evaluations. The nature of the assessed procedures prevents masking the study investigators and patients to group assignment. ETHICS AND DISSEMINATION: All participants will provide written informed consent. The ethics committee ‘Comité de Protection des Personnes Ile de France VII’ approved this study on 2 April 2021 (No 2021-000989-15). Study findings will be submitted for publication and presented at relevant conferences. TRIAL REGISTRATION NUMBER: NCT04949633.