Objectives: To explore antioxidant (vitamin E) effects during pregnancy at high altitude (3000 m) on pregnancy outcomes. Methodology: Thirty-six pregnant Wistar rats, born and maintained at high altitude, were divided into three groups: Vitamin E-treated (vitamin E dissolved in olive oil), vehicle- treated (olive oil), and control (no treatment) groups. The mean hemoglobin concentration and hematocrit were estimated and used as indices for maternal hypoxia. The number of pups and their birth weight were determined. Placental oxidant conditions were assessed using placental malondialdehyde (MDA) levels and placental antioxidant enzyme activity was determined by superoxide dismutase (SOD) and glutathione peroxidase (GPX). Placentae were then examined histologically, and the average percentage of villi with syncytial knots, cytotrophoblastic cells, and fetal capillaries were used as indices of placental hypoxia. Results: Vitamin E-treated pregnant rats had less maternal and placental hypoxia than control and vehicle-treated groups. The vitamin E-treated group showed a higher number of newborn pups than control and vehicle-treated groups. Conclusion: Vitamin E administration to pregnant rats at high altitude may improve birth outcome by improving both maternal and placental hypoxia. Controlled trial studies to investigate the effect of vitamin E therapy on pregnancy outcomes in pregnant women at high altitude are recommended.