Modern obstetrics: beyond early delivery for fetal or maternal compromise

Abstract

Abstract The ARRIVE trial showed that adverse perinatal outcomes among low-risk nulliparous women at 39 weeks’ gestation were lower following labor induction (4.3%) compared with expectant management (5.4%; P value 0.049). Although this difference was deemed to be not statistically significant (since the significance threshold had been set at 0.046), there is a need to interpret trial results using a Bayesian approach and to review the conceptual significance of trial findings. The ARRIVE trial hypothesis represents a challenge to the central paradigm of modern obstetrics because it abandons maternal or fetal compromise as a pre-requisite for early delivery. The P value function based on the ARRIVE trial shows that study findings are not consistent with even a modest increase in adverse perinatal outcomes following labor induction for 39 weeks’ gestation, and instead, consistent with a substantial reduction in adverse perinatal outcomes. Physiologic evidence, epidemiologic evidence (on gestational age-specific rates of pregnancy complications, fetal growth-restriction and perinatal morbidity and mortality), and meta-analyses of related randomized trials show that pregnancies accrue small and progressively increasing risks of adverse outcomes at later gestation. Bayesian analysis, based on previous randomized trials updated with ARRIVE trial results, also shows that labor induction for 39 weeks’ gestation has a protective effect with regard to adverse perinatal outcomes. Obstetricians need to be cognizant of this balance of risks and benefits with regard to labor induction and expectant management at 39 weeks’ gestation and beyond, though as always, the ultimate valuation in decision-making has to be guided by principles of patient autonomy.