There is biological plausibility for vitamin D to play a role in pregnancy outcomes, given the presence of receptors in gestational tissues. Data has progressed since the ACOG committee opinion regarding vitamin D supplementation in pregnancy released in 2011. Does low maternal vitamin D actually affect maternal outcomes? In the session we will review the latest data from “Current Opinions in OB/GYN” regarding vitamin D supplementation in pregnancy, focusing on preeclampsia risk and GDM.