Outpatient balloon catheter vs inpatient prostaglandin for induction of labour (OBLIGE): a randomised controlled trial

BACKGROUND: Approximately one in four pregnant women undergo an induction of labour. The purpose of this study is to investigate the clinical effectiveness, safety, and cost-effectiveness for mothers and babies of two methods of cervical ripening – inpatient care for women starting induction with vaginal prostaglandin E2 hormones, or allowing women to go home for 18 to 24 h after starting induction with a single-balloon catheter. METHODS/DESIGN: This is a multi-centre randomised controlled trial in New Zealand. Eligible pregnant women, with a live singleton baby in a cephalic presentation who undergo a planned induction of labour at term, will be randomised to outpatient balloon-catheter induction or in-hospital prostaglandin induction. The primary outcome is caesarean section rate. To detect a 24% relative risk reduction in caesarean rate from a baseline of 24.8%, with 80% power and 5% type 1 error, will require 1552 participants in a one to one ratio. DISCUSSION: If outpatient balloon-catheter induction reduces caesarean section rates, has additional clinical benefits, and is safe, cost-effective, and acceptable to women and clinicians, we anticipate change in induction of labour practice around the world. We think that home-based balloon-catheter induction will be welcomed as part of a patient-centred labour-induction care package for pregnant women. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry (ANZCTR), ACTRN: 12616000739415. Registered on 6 June 2016.