Outpatient elective induction of labour at 39 weeks' gestation (HOME INDUCTION): an open-label, randomised, controlled, phase III, non-inferiority trial.

Background: The increased demand for induction of labour (IOL) at 39 weeks' gestation in normal-risk nulliparous patients creates significant logistical challenges for busy maternity units. A potential innovation is commencing induction by means of outpatient cervical ripening, using either a vaginal prostaglandin preparation (Propess) or an osmotic cervical dilator (Dilapan-S).

Methods: A Phase III, open label, single centre non-inferiority trial (EudraCT number 2019-004697-25) randomised healthy nulliparous women who chose elective IOL at 39 weeks to one of three methods of initial cervical ripening, specifically 12 h of Dilapan-S(D12), 24 h of Dilapan-S(D24), or 24 h of Propess(P24) between November 2020 and July 2023. After initial administration of the IOL agent in the hospital, participants returned home for 12 or 24 h, before readmission to complete delivery. The primary outcome was vaginal delivery achieved at any time, and this was compared in a non-inferiority analysis of Dilapan-S compared to Propess, within a 10% non-inferiority margin. Secondary outcomes included pairwise comparisons for each induction agent, and a range of logistical factors, such as time to delivery, the need for an additional cervical ripening agent, and length of hospital stay.

Findings: Of the 327 women randomised at 38 weeks, 271 (83%) completed the induction intervention. The D24 and P24 groups showed similarly high rates of vaginal delivery, 75% and 76% respectively. D12 had a lower vaginal delivery rate of 64% and consequently the overall comparison of Dilapan-S to Propess did not demonstrate non-inferiority (difference = -6%, 95% CI = -17%, 5%) because the lower 95% CI exceeded the -10% threshold of non-inferiority. The majority of participants across all groups were delivered by any means within 72 h of starting the induction process, inclusive of time spent at home (89% of the D24 group, 98% of the D12 group, 95% of the P24 group). There were no differences in rates of adverse events between groups.

Interpretation: There were similarly high vaginal delivery rates for D24 and P24, with at least 75% of patients successfully delivering vaginally following outpatient cervical ripening, with no significant adverse maternal or neonatal outcomes.

Funding: The Rotunda Foundation, Medicem Technology s.r.o.