Cesarean delivery rates have plateaued in the United States despite attempts at reduction. Patients undergoing cesarean delivery are at greater risk for both short- and long-term complications when compared to those undergoing vaginal delivery. Previous studies have also suggested structural factors including the day of week and the time of decision for cesarean delivery play a role in the rate of cesarean delivery. The aim of the study is to determine if cesarean delivery rate varies by day of week and start time of induction.

We conducted a retrospective cohort study of nulliparous women who delivered at The Children’s Hospital at OU Medical Center. We included patients that underwent an induction of labor (IOL) between July 1, 2017 and June 30, 2022 at or beyond 37wks gestation with singleton gestations and between the ages of 15-49. Patients with known fetal anomaly, fetal demise or intraamniotic infection prior to induction of labor were excluded. The primary outcome was the cesarean delivery rate between patients who started induction of labor on a weekend compared to weekday as well as those that started during the night shift compared to the day shift. Secondary outcomes examined associated maternal and neonatal morbidity and mortality. Bivariate comparisons of cesarean deliveries and secondary outcomes were conducted using Chi-square or Fisher’s exact test, as appropriate. Unadjusted and adjusted risk ratios and 95% confidence intervals (CI) for the associations between IOL timing and the primary outcome of incidence of cesarean deliveries, as well as the secondary outcomes of composite adverse maternal and neonatal outcomes, were estimated using modified Poisson regression. A p-value <0.05 was considered statistically significant.

1185 patients underwent induction of labor and met inclusion criteria. The cesarean delivery rate was similar between the two groups with a rate of 26.4% for those who started their IOL on the weekday and 25% in those who started their IOL on the weekend (p=0.66). The cesarean delivery rate was additionally similar between those starting their IOL during the nightshift versus day shift with a rate of 24.9% and 27.2% respectively (p=0.38). Adjusted risk ratio (aRR) for cesarean delivery with IOL on a weekend vs weekday was 0.98 (95% CI 0.77, 1.26). aRR for cesarean delivery with IOL on the night vs day shift was 0.92 (95% CI 0.76, 1.11). Additionally, aRR for composite adverse maternal outcomes and composite adverse neonatal outcomes were no different between the two cohorts when comparing IOL on weekend vs weekday and night vs day shift.

Our study does not support a difference in the incidence of cesarean deliveries based on the timing of IOL initiation.