Importance of Vitamin D during Pregnancy Vitamin D supplementation during pregnancy in women with low vitamin D status may improve fetal growth and reduce the risks for small-for-gestational-age, preeclampsia, preterm birth, and gestational diabetes.Vitamin D deficiency is thought to be common among pregnant women in some populations, and has been found to be associated with an increased risk of pre-eclampsia, gestational diabetes mellitus, preterm birth, and other tissue-specific conditions. Meet Expert Gynecologist Dr. Dipak Kolte @ Kotle Hospital, Ravet