ObjectiveTo investigate whether staffing levels of maternity units affect prelabor urgent, elective, and intrapartum cesarean delivery rates.MethodsThis population-based retrospective cohort study covers the deliveries of the 11 hospitals of a French perinatal network in 2008–2014 (N = 102 236). The independent variables were women’s demographic and medical characteristics as well as the type, organization, and staffing levels for obstetricians, anesthesiologists, and midwives of each maternity unit. Bivariate and multivariate analyses were conducted with multilevel logistic models.ResultsOverall, 23.9% of the women had cesarean deliveries (2.4% urgent before labor, 10% elective, and 11.5% intrapartum). Independently of individual- and hospital-level factors, the level of obstetricians, measured by the number of full-time equivalent persons (i.e., 35 working hours per week) per 100 deliveries, was negatively associated with intrapartum cesarean delivery (adjusted odds ratio, aOR 0.55, 95% confidence interval, CI 0.36–0.83, P-value = 0.005), and the level of midwives negatively associated with elective cesarean delivery (aOR 0.79, 95% CI 0.69–0.90, P-value < 0.001). Accordingly, a 10% increase in obstetrician and midwife staff levels, respectively, would have been associated with a decrease in the likelihood of intrapartum cesarean delivery by 2.5 percentage points and that of elective cesarean delivery by 3.4 percentage points. These changes represent decreases in intrapartum and elective cesarean delivery rates of 19% (from 13.1% to 10.6%) and 33% (from 10.3% to 6.9%), respectively.ConclusionStaffing levels of maternity units affect the use of cesarean deliveries. High staffing levels for obstetricians and midwives are associated with lower cesarean rates.