Ascorbate prevents placental oxidative stress and enhances birth weight in hypoxic pregnancy in rats

•  High‐altitude pregnancy is associated with reduced oxygenation and placental complications, which can affect maternal and fetal outcome. However, most high‐altitude populations are also impoverished and because maternal undernutrition itself is known to promote placental problems, the extent to which complications during high‐altitude pregnancy could be due to maternal oxygen and/or nutrient restriction remains unclear. •  The aim of the study was to investigate whether reduced placental oxygenation, independent of maternal undernutrition, increases maternal and placental oxidative stress and whether maternal treatment with vitamin C is protective. •  The study shows that hypoxic pregnancy increased maternal circulating and placental molecular indices of oxidative stress. •  Maternal vitamin C treatment was protective and increased birth weight. •  The study offers insight to mechanism and intervention against the effects of high altitude on pregnancy.