The role of placental VEGFA in placental development and maternal pregnancy adaptations is unknown. In this thesis, one or both copies of Vegfa was knocked out from the placental spongiotrophoblast region using a mouse Cre-loxP system. Surprisingly, in pregnancies carrying 100% conceptuses with a single deletion of Vegfa from the spongiotrophoblast layer, maternal circulating VEGFA increased by 20% accompanied by a 15% decrease in arterial pressure while no impairment in embryo growth was found. In pregnancies carrying 50% conceptuses with both copies of Vegfa deleted from spongiotrophoblast, 17% of conceptuses had been reabsorbed by late gestation suggesting a function for spongiotrophoblast VEGFA in sustaining early pregnancy. In conclusion, spongiotrophoblast VEGFA affects maternal function during pregnancy but the exact mechanism remains to be defined.