Vitamin D requirements during pregnancy.

Adequate vitamin D concentrations during pregnancy are necessary to ensure appropriate maternal responses to the calcium demands of the fetus and neonatal handling of calcium. The purpose of this report is to review studies that investigated maternal and neonatal outcomes of vitamin D deficiency or supplementation during pregnancy. Most studies reported included women at high risk of vitamin D deficiency, because of low vitamin D and calcium intake or decreased ability to synthesize endogenous vitamin D (attributable to lack of sun exposure or to heavily pigmented skin). Overall, vitamin D supplementation in these populations leads to improved neonatal handling of calcium. Results concerning benefits for fetal growth and bone development are inconclusive. There is no evidence of a benefit of supplementation during pregnancy above amounts routinely required to prevent vitamin D deficiency.