The effect of time of day on outcome of unscheduled cesarean deliveries

Objective. To assess the association between time of day and characteristics and complications rate of cesarean sections. Methods. We conducted a retrospective cohort study of all women who underwent an unscheduled (non-elective) cesarean section (CS) between 1997 and 2007 in a single tertiary medical center. Maternal and neonatal outcome and duration of CS were analyzed according to the work shift. Multivariable logistic regression analysis was used to determine whether shift number is an independent risk factor for maternal or neonatal adverse outcome. Results. There were overall 9944 unscheduled CS during the study period, of them 2995 (30.1%) were operated on the morning shift, 4618 (46.4%) on the evening shift, and 2331 (23.5%) on the night shift. The characteristics of the women in each of the shifts were overall similar. Women who underwent CS during night shift had a higher rate of endometritis and wound infection, postpartum hemorrhage requiring hemotransfusion, and prolonged postoperative hospitalization. The rate of adverse neonatal outcome was similar in the three working shifts. After adjustment for potential confounders by multivariable logistic regression analysis, maternal morbidity was significantly higher for women operated on night shift. The risk of neonatal morbidity was unrelated to the working shift. Overall duration of CS, time required for induction of anesthesia, and net operation time were all significantly higher during the night shift compared with the morning and evening shift. Conclusion. CSs performed during night shift are associated with longer operative time and an increased risk for maternal, but not neonatal, morbidity.