Characteristics Associated with Induction of Labor and Delivery Route Among Primiparous Women with Term Deliveries in the Listening to Mothers III Study.

Background: Induction of labor (IOL) is increasingly common in the United States, yet characteristics associated with IOL among primiparous women delivering at term are not well understood.

Materials And Methods: Data from the Listening to Mothers III study, a survey of women aged 18-45 with singleton deliveries in U.S. hospitals in 2011-2012, were utilized. Weighted logistic regression models examined predictors of IOL among 924 primiparous women with term deliveries. Associations of maternal characteristics with delivery route (cesarean and vaginal delivery) were examined among primiparous women induced at term.

Results: Four hundred twenty-three (45.8%) primiparous women with term deliveries underwent IOL; subjective reasons were reported by 53% of induced women. Women who were married (odds ratios [OR] = 1.8, 95% confidence intervals [CI] 1.2-2.9), felt pressure from a provider for IOL (OR = 3.5, 95% CI 2.0-6.2), and whose provider was concerned about the size of the baby (OR = 1.9, 95% CI 1.2-2.9) were significantly more likely to undergo IOL. Nearly 30% of primiparous women who underwent IOL at term had a cesarean delivery (CD). Among the induced women, those who were overweight/obese (OR = 4.9, 95% CI 2.5-10.0), felt pressure from a provider for CD (OR = 8.6, 95% CI 3.5-21.2), and whose provider suspected the baby might be getting large near end of pregnancy (OR = 2.7, 95% CI 1.1-7.0) were significantly more likely to have CD.

Conclusions: In this study, nearly half of the primiparous women with term deliveries underwent IOL, with a sizeable proportion reporting subjective reasons for induction. A better understanding of the characteristics associated with IOL at term may help reduce unnecessary interventions and, ultimately, primary CD.