<qa>  What is the prevalence of hypovitaminosis D in reproductive age women?The prevalence of hypovitaminosis D in reproductive aged African-American women occurs at a rate of 40. Two factors have contributed to this public health problem: an inadequate DRI for vitamin D and avoidance of sun exposureuse of sunscreen. This startling rate of hypovitaminosis D requires that the DRI for vitamin D in pregnancy be evaluated in a detailed manner. The Cochrane Library 2002 released a report stating that there is insufficient data to evaluate the effects of vitamin D supplementation during pregnancy. Recently, the safety of prolonged supplementation with up to 25xs DRI 10,000 IUday was demonstrated in nonpregnant adults. It is essential to determine what dose of vitamin D is required to eliminate hypovitaminosis D during pregnancy and provide the fetusneonate with adequate vitamin D stores during development and growth, particularly in darkly pigmented individuals. The aim of this research proposal, then, is to determine the efficacy, effectiveness, and safety of maternal vitamin D supplementation as a function of ethnicity and UV exposure in the prevention of hypovitaminosis D in the pregnant mother and her fetusneonate. We hypothesize that darkly pigmented mothers will require substantially higher oral supplementation with vitamin D to eliminate hypovitaminosis D as compared to their Caucasian counterparts. We propose a comprehensive clinical trial to test our hypothesis. Mothers at 12 weeks gestation will be randomized to one of three vitamin D treatment groups: 