Bayesian Scepsis About SWEPIS: Quantifying the Evidence That Early Induction of Labour Prevents Perinatal Deaths

In a recent randomized clinical trial, Wennerholm and colleagues compared induction of labour at 41 weeks with expectant management and induction at 42 weeks. The trial was stopped early, because six perinatal deaths occurred in the expectant management group, whereas none occurred in the induction group. Our Bayesian reanalysis finds that the SWEPIS data indeed support the hypothesis that induction of labour at 41 weeks of pregnancy is associated with a lower rate of stillbirths. However, the degree of this support is moderate at best, and arguably provides insufficient ground for terminating the study. In general, it seems hazardous to terminate clinical studies on the basis of a single P<0.05 result, without converging support of a Bayesian analysis.