Labor induction and the risk of a cesarean delivery among nulliparous women at term

Objective: To estimate the association of labor induction with the risk of a cesarean delivery for nulliparous women presenting at term at a regional hospital. Methods: This was a retrospective cohort study of cesarean delivery among nulliparous women delivering a live, singleton, vertex pregnancy at term. We used clinical data from electronic hospital obstetric records at a large, regional, obstetric hospital, approximating a population-based cohort. Multivariable logistic regression was used to explore risk factors associated with cesarean delivery, and the fraction of cesarean deliveries attributable to the use of labor induction was estimated. Results: From a cohort of 24,679 women, 7,804 met inclusion criteria. Labor induction was used in 43.6% of cases, 39.9% of which were elective. Use of labor induction was associated with an increased odds of cesarean delivery (crude odds ratio 2.67, 2.40-2.96) and the association remained significant (adjusted odds ratio 1.93, 1.71-2.2) after adjustment for maternal demographic characteristics, medical risk, and pregnancy complications. The contribution of labor induction to cesarean delivery in this cohort was estimated to be approximately 20%. Conclusion: Labor induction is significantly associated with a cesarean delivery among nulliparous women at term for those with and without medical or obstetric complications. Reducing the use of elective labor induction may lead to decreased rates of cesarean delivery for a population.