Influence of time of delivery on risk of adverse neonatal outcome in different size of delivery units: a retrospective cohort study in Finland

AbstractPurpose: To evaluate the impact of time of birth on adverse neonatal outcome in singleton term hospital births.Materials and methods: Medical Birth Register Data in Finland from 2005 to 2009. Study population was all hospital births (n = 263,901), excluding multiple pregnancies, preterm births <37 weeks, major congenital anomalies or birth defects, and antepartum stillbirths. Main outcome measures were either 1-minute Apgar score 0–3, 5-minute Apgar score 0–6, or umbilical artery pH <7.00, and intrapartum and early neonatal mortality. We calculated risk ratios (ARRs) adjusted for maternal age and parity, and 95% confidence intervals (CIs) to indicate the probability of adverse neonatal outcome outside of office hours in normal vaginal delivery, in vaginal breech delivery, in instrumental vaginal delivery, and in elective and nonelective cesarean sections. We analyzed different size-categories of maternity hospitals and different on-call arrangements.Results: Instrumental vaginal delivery had incre...