Birth during off-hours: Impact of time of birth, staff´s seniority, and unit volume on maternal adverse outcomes-a population-based cross-sectional study of 87 065 deliveries.

Background: The aim of this study was to investigate whether time of birth, unit volume, and staff seniority impact the incidence of maternal complications in deliveries ≥34 + 0 gestational weeks.

Methods: We conducted a population-based cross-sectional study of 87 065 deliveries occurring between 2004 and 2015 in ten public hospitals in Styria, Austria. A composite adverse maternal outcome measure of uterine atony, postpartum hysterectomy, postpartum bleeding, impaired wound healing, postpartum infections requiring antibiotic treatment, sepsis, or maternal death was used to compare outcomes by time of birth, unit volume, and staff seniority.