Co-morbidity of PCOS and vitamin D deficiency is a frequent combination. 80% of PCOS patients have vitamin D deficiency, most of them severe.In generally, vitamin D deficiency might cause spontaneous abortion during the first trimester, bacterial vaginosis, sensibility for infections and related spontaneous abruption of amnionic membrane, and preterm delivery. Vitamin D deficiency and also PCOS might elevate the risk of gestational diabetes mellitus and preeclampsia. In respect of the newborns, following both alterations of the mother, we can see elevated risk for lower birth weight, size and bone development disorders, however, later, higher risk of T1DM and metabolic syndrome. Parallel occurance of these co-morbidities might cause additive risk for the above mentioned disorders. Common pregnant vitamins contains 4-600 IU vitamin D/ pill, which is inadequate for supplementation for the mothers – additive vitamin D intake (cc. up to 1500-2000 IU/day) is necessary for maintaining the mother’s vitamin D level preventing hypovitaminosis; or more, if we find hypovitaminosis before or in the beginning of the pregnancy. This review thinks over the diseases, might occur; the risk factors, which can draw the atention for the chance of hypovitaminosis and some therapeutic aspects for supplementation.