Vitamin-D (vit-D) deficiency among pregnant women is frequent in many populations over the world and this is a preventable health problem. Research indicates that adequate vit-D intake in pregnancy should be optimal for both maternal and fetal health, because calcium demands increase in the third trimester of pregnancy that is why vit-D status becomes crucial for maternal health, fetal skeletal growth with good and optimal outcomes. Vit-D deficiency or overdose during pregnancy is the origin for a host of future perils for the child, especially the effect on neurodevelopment and the immune system. Therefore, prevention of vit-D deficiency or overdose among pregnant women is essential and demanding. The currently recommended supplementation amount of vit-D is not sufficient to maintain a value of 25 hydroxy vit-D during pregnancy. This review discusses vit-D metabolism, dietary requirements, recommendations and implications of vit-D deficiency during pregnancy and lactation.