Elective induction of labor as a risk factor for cesarean delivery among low-risk women at term.

OBJECTIVE To determine the effects of elective induction on the risk of cesarean delivery in a cohort of women with low-risk term pregnancies and to evaluate the costs of elective induction services within our hospital system. METHODS Records of 1135 eligible women with low-risk, singleton, vertex pregnancies at 38-41 weeks' gestation who were eligible for vaginal delivery were analyzed retrospectively after elective induction (n = 263) or spontaneous labor (n = 872). Outcome measures included cesarean delivery and direct costs. Variables evaluated were parity, maternal age, estimated gestational age, birth weight, prior cesarean delivery, epidural anesthetic use, and provider category. Analysis was by univariable and multivariable regression modeling. RESULTS Elective induction placed nulliparas at a twofold higher risk for cesarean delivery (odds ratio 2.4, 95% confidence interval 1.2, 4.9) after adjustment for birth weight, maternal age, and gestational age. We found a significantly increased risk of cesarean delivery with increased birth weight for nulliparas (2-66.7%). Increasing maternal age increased the risk of cesarean delivery in all parity groups (P <.05), but particularly among nulliparas (3-26.3%) (P <.001). Electively induced labors that ended in vaginal delivery cost $273 more and required an average of 4 hours more in the hospital before delivery than did noninduced vaginal deliveries (P <.001). CONCLUSION Elective induction significantly increased the risk of cesarean delivery for nulliparas, and increased in-hospital predelivery time and costs.