Association between time of day and performance, indications, and outcomes of obstetric interventions among nulliparous women delivering at term

Objectivethe objective of this study is to determine whether there is an association between delivery time and obstetric interventions, as well as maternal and perinatal outcomes.study designretrospective cohort study of nulliparous women delivering singleton, vertex, live births at ≥37 weeks gestation at a single center from 2014 to 2015. nighttime deliveries were designated as those occurring between 18:00 and 05:59 h. the primary outcomes were obstetrical interventions (cesarean delivery, operative vaginal delivery, episiotomy). secondary outcomes included indications for operative deliveries, as well as maternal and perinatal outcomes.resultsof 7691 women eligible for inclusion, 3707 (48.2%) delivered during the nighttime. women who experienced nighttime deliveries had no demographic or clinical differences compared with women delivering during the daytime. women delivering during the nighttime had greater odds of cesarean delivery (or 1.27, 95% ci 1.14–1.43) and operative vaginal delivery (or 1.83, 95% ci 1.20–2.78). women who delivered at night were also more likely to have neonates with a 5 min apgar score <7 (or 1.59, 95% ci 1.08–2.32) and umbilical artery ph < 7.0 (or 1.76, 95% ci 1.18–2.63). there were no differences observed in any of the other outcomes examined.conclusionsdelivery during the nighttime is associated with alterations in some obstetric interventions and perinatal outcomes