Modern obstetrics: beyond early delivery for fetal or maternal compromise

The results of A Randomized Trial of Induction Versus Expectant Management trial showed that adverse perinatal outcomes among low-risk nulliparous women at 39 weeks' gestation were lower after labor induction (4.3%) than expectant management (5.4%; P=.049). Although this difference was deemed to be not statistically significant (because the significance threshold had been set at .046), there is a need to interpret trial results using a Bayesian approach and to review the conceptual significance of trial findings. The hypothesis of A Randomized Trial of Induction Versus Expectant Management represents a challenge to the central paradigm of modern obstetrics because it abandons maternal or fetal compromise as a prerequisite for early delivery. The P value function based on A Randomized Trial of Induction Versus Expectant Management trial shows that study findings are not consistent with even a modest increase in adverse perinatal outcomes after labor induction for 39 weeks' gestation and, instead, consistent with a substantial reduction in adverse perinatal outcomes. Physiological 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 a later gestation. Bayesian analysis, based on previous randomized trials updated with A Randomized Trial of Induction Versus Expectant Management trial results, also shows that labor induction for 39 weeks' gestation has a protective effect regarding adverse perinatal outcomes. Obstetricians need to be cognizant of this balance of risks and benefits regarding labor induction and expectant management at 39 weeks' gestation and beyond, although, as always, the ultimate valuation in decision making has to be guided by principles of patient autonomy.

Automated summary

The results of a randomized trial comparing induction and expectant management at 39 weeks' gestation suggest that induction may lower adverse perinatal outcomes for low-risk nulliparous women. However, a Bayesian analysis supports this finding and challenges the current obstetric paradigm. Obstetricians need to carefully consider the balance of risks and benefits when deciding between induction and expectant management, with patient autonomy playing a vital role in decision-making.