Hypoxia causes reductions in birth weight by altering maternal glucose and lipid metabolism.

Hypoxia of residence at high altitude (>2500 m) decreases birth weight. Lower birth weight associates with infant mortality and morbidity and increased susceptibility to later-in-life cardiovascular and metabolic diseases. We sought to determine the effects of hypoxia on maternal glucose and lipid metabolism and their contributions to fetal weight. C57BL6/NCrl mice, housed throughout gestation in normobaric hypoxia (15% oxygen) or normoxia, were studied at mid (E9.5) or late gestation (E17.5). Fetal weight at E17.5 was 7% lower under hypoxia than normoxia. The hypoxic compared with normoxic dams had ~20% less gonadal white adipose tissue at mid and late gestation. The hypoxic dams had better glucose tolerance and insulin sensitivity compared with normoxic dams and failed to develop insulin resistance in late gestation. They also had increased glucagon levels. Glucose uptake to most maternal tissues was ~2-fold greater in the hypoxic than normoxic dams. The alterations in maternal metabolism in hypoxia were associated with upregulation of hypoxia-inducible factor (HIF) target genes that serve, in turn, to increase glycolytic metabolism. We conclude that environmental hypoxia alters maternal metabolism by upregulating the HIF-pathway, and suggest that interventions that antagonize such changes in metabolism in high-altitude pregnancy may be helpful for preserving fetal growth.