Effects on the Fetus of Maternal Oxygen Administration

Oxygen is commonly administered to most patients receiving obstetric anesthesia, presumably to benefit the fetus. The physiology of maternal oxygen administration, the complex anatomy and physiology of the maternal-fetal-placental unit, and the differential handling of oxygen metabolites in the fetus compared to the adult all confound a simple relationship between maternal oxygen and fetal outcome. Maternal oxygen administered for elective cesarean delivery under regional analgesia can only modestly increase fetal oxygenation. Under general anesthesia, and in cases of fetal compromise, maternal oxygen administered during either cesarean or vaginal delivery increases fetal oxygenation, particularly oxygen content, to a greater extent. General outcome measures, however, have failed to show any improvement in fetal status, and there are some theoretical concerns about hyperoxia-induced oxygen free radicals. Therefore, it may not be necessary to administer oxygen to healthy women without evidence of fetal compromise who are undergoing routine cesarean delivery under regional anesthesia.