Vitamin D in pregnancy and breastfeeding

Vitamin D, which is synthesized in skin exposed to UV light, or is consumed in the diet, plays a key role in maintaining bone integrity via the regulation of calcium and phosphorus homeostasis. It also influences a number of extra-skeletal processes, including immune function and blood glucose homeostasis. Maternal vitamin D deficiency in pregnancy leads to poor fetal skeletal mineralization in utero that can manifest as rickets in newborns. In addition to skeletal effects, women with very low vitamin D status face increased risks of other adverse pregnancy outcomes and possible long-term effects on their own health and that of their offspring. However, controversy remains over definitions of vitamin D sufficiency and deficiency, complicating recommendations on maternal intakes. At a minimum, all pregnant women should take a supplement of 400 IU/day, in addition to sensible sun exposure and increasing their intake of food sources.