Multicentre double-blind randomised placebo-controlled four-arm trial to assess the effect of oral sodium bicarbonate and intravenous hyoscine butylbromide on spontaneous delivery after induction of labour in nulliparous women: protocol for the Safe Induction of Labour Trial (SAINT)

Abstract

Introduction Presently, more than one in four births in high-income countries undergo labour induction. Induction of labour is an independent risk factor for adverse obstetric outcomes, including high rates of operative delivery. Two drugs, hyoscine butylbromide and sodium bicarbonate, have been used in labour to facilitate cervical dilation and prevent uterine lactate accumulation. However, no previous randomised trial has systematically studied the separate and combined effects of these drugs in women with induction of labour.Methods and analysis The Safe Induction of Labour Trial (SAINT) study will assess the efficacy of oral sodium bicarbonate and intravenous hyoscine butylbromide on facilitating spontaneous (ie, non-operative) delivery in nulliparous participants with induction of labour. We present a 2×2 factorial design where three active treatment arms are compared with double-placebo. Participants are recruited at 10 delivery departments across Norway. Treatment will start on diagnosis of established labour with a maximum of three consecutive doses 4 hours apart. Approximately 5100 women will be screened to achieve 3000 participants randomly assigned to study intervention.Statistical analyses The primary outcome of spontaneous delivery will be analysed using binary logistic regression. Results will be presented as marginal adjusted risk differences between each of the three active treatment groups and the double-placebo group.Ethics and dissemination The SAINT study is approved by the Regional Committee for Medical and Health Research Ethics, the European Union Clinical Trials Information System, the Norwegian Medical Products Agency and Institutional Review Boards. Results will be disseminated in peer-reviewed journals and communications to congresses.Trial registration number Clinical Trials: NCT05719467. EudraCT/EUCT: 2021-000392-37/2024-511848-55-00.