Induction of Labour at 41 Weeks Versus Expectant Management Until 42 Weeks (INDEX): Multicentre, Randomised Non-inferiority Trial

Abstract Objective To compare induction of labour at 41 weeks with expectant management until 42 weeks in low risk women. Design Open label, randomised controlled non-inferiority trial. Setting 123 primary care midwifery practices and 45 hospitals (secondary care) in the Netherlands, 2012-16. Participants 1801 low risk women with an uncomplicated singleton pregnancy: randomised to induction (n=900) or to expectant management until 42 weeks (n=901). Interventions Induction at 41 weeks or expectant management until 42 weeks with induction if necessary. Primary outcome measures Primary outcome was a composite of perinatal mortality and neonatal morbidity (Apgar score Results Median gestational age at delivery was 41 weeks+0 days (interquartile range 41 weeks+0 days-41 weeks+1 day) for the induction group and 41 weeks+2 days (41 weeks+0 days-41 weeks+5 days) for the expectant management group. The primary outcome was analysed for both the intention-to-treat population and the per protocol population. In the induction group, 15/900 (1.7%) women had an adverse perinatal outcome versus 28/901 (3.1%) in the expectant management group (absolute risk difference −1.4%, 95% confidence interval −2.9% to 0.0%, P=0.22 for non-inferiority). 11 (1.2%) infants in the induction group and 23 (2.6%) in the expectant management group had an Apgar score Conclusions This study could not show non-inferiority of expectant management compared with induction of labour in women with uncomplicated pregnancies at 41 weeks; instead a significant difference of 1.4% was found for risk of adverse perinatal outcomes in favour of induction, although the chances of a good perinatal outcome were high with both strategies and the incidence of perinatal mortality, Apgar score Trial registration Netherlands Trial Register NTR3431.