Does maternal oxygen administration during non-reassuring fetal status affect the umbilical artery gas measures and neonatal outcomes?

Purpose To clarify whether maternal oxygen administration during vaginal delivery improves umbilical artery (UA) gas measurements and neonatal outcomes. Methods Singleton pregnancies requiring operative vaginal delivery or emergency cesarean section (CS) due to non-reassuring fetal status (NRFS) during vaginal delivery at our hospital from 2018 to 2021 were retrospectively investigated. Intrapartum fetal wellbeing was evaluated based on the 5-tier fetal heart rate (FHR) pattern which is a delivery management method widely used in Japan. Operative vaginal deliveries or emergency CS was performed under integrated judgment in NRFS. Patients were divided into the oxygen group to whom oxygen (10 L/min) was supplied by a facemask and the room air group. The UA gas measurements and neonatal outcomes were compared. The oxygen administration was classified by conditions before and after the coronavirus disease 2019 pandemic. As a secondary evaluation, stratification of FHR pattern levels and factors associated with UA pH