Intrapartum Maternal Oxygen Supplementation: Effects on the Mother and Neonate

Approximately 2/3 of laboring women receive supplemental oxygen (O2) in an attempt to reverse perceived fetal hypoxia on electronic fetal monitoring (EFM). O2 supplementation is most commonly used in patients with Category II EFM, a class of EFM patterns designed in part to identify fetal acidemia. This liberal use of O2 in laboring patients is concerning because hyperoxygenation in infants is associated with adverse outcomes including retinopathy and abnormal neurodevelopment. Furthermore, excess O2 exposure is linked to free radical generation and subsequent oxidative cell damage. This calls for a closer look at the safety of intrauterine O2 exposure. The proposed project explores potential mechanisms for harm with maternal O2 supplementation in laboring patients with Category II EFM. Specifically, this project will determine the effect of O2, compared to room air (RA), on umbilical cord and maternal levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), markers of free radical-induced oxidative stress. The study will also explore the correlation between urinary and blood markers of oxidative stress. Banked specimens will be used to investigate the potential effect of peripartum O2 exposure on placental oxidative stress in the future.