Abstract
Objective Findings of the recent ARRIVE (A Randomized Trial of Induction Versus Expectant Management) trial, showing reduced cesarean risk with elective labor induction among low-risk nulliparous women at 39 weeks' gestation, have the potential to change interventional delivery practices but require examination in wider populations. The aim of this study was to identify whether term induction of labor was associated with reduced cesarean delivery risk among women with obesity, evaluating several maternal characteristics associated with obesity, induction, and cesarean risk.
Study Design We studied administrative records for 66,280 singleton, term births to women with a body mass index ≥30, without a prior cesarean delivery, in New York City from 2008 to 2013. We examined elective inductions in 39 and 40 weeks' gestation and calculated adjusted risk ratios for cesarean delivery risk, stratified by parity and maternal age. We additionally evaluated medically indicated inductions at 37 to 40 weeks among women with obesity and diabetic or hypertensive disorders, comorbidities that are strongly associated with obesity.
Results Elective induction of labor was associated with a 25% (95% confidence interval: 19–30%) lower adjusted risk of cesarean delivery as compared with expectant management at 39 weeks of gestation and no change in risk at 40 weeks. Patterns were similar when stratified by parity and maternal age. Risk reductions in week 39 were largest among women with a prior vaginal delivery. Women with comorbidities had reduced cesarean risk with early term induction and in 39 weeks.
Conclusion Labor induction at 39 weeks was consistently associated with reduced risk of cesarean delivery among women with obesity regardless of parity, age, or comorbidity status. Cesarean delivery findings from induction trials at 39 weeks among low-risk nulliparous women may generalize more broadly across the U.S. obstetric population, with potentially larger benefit among women with a prior vaginal delivery.
Key Points
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We found reduced cesarean risk with induction at 39 weeks.
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Results were consistent for age and comorbidity subgroups.
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Risk reductions were largest among multiparous women.
Keywords
ARRIVE - body mass index - cesarean delivery - induction - obesity
