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 potential effect of
peripartum O2 exposure on placental oxidative stress. We will also use magnetic resonance
imaging to investigate the effect of in utero hyperoxygenation on the neonatal brain.