Various observational studies implicated the potential role of vitamin D in maternal, fetal, neonatal and infant health. Vitamin D deficiency could influence the development of gestational diabetes, pre-eclampsia, fetal growth restriction and different childhood diseases such as lower respiratory tract infection and eczema. We do not yet have any exact data on the prevalence of vitamin D insufficiency in different age and risk subgroups of the Slovenian population. While Slovenian guidelines for vitamin D supplementation in infants already exist, there are no guidelines for vitamin D supplementation in pregnant women. This article explains vitamin D physiology in pregnancy and the role of sufficient vitamin D concentration in the health of pregnant women, fetuses and neonates.