Vitamin D Requirements in Pregnancy/Lactation

In our study (latitude 32o), of the 277 women, 102 had a baseline 25(OH)D <20 ng/mL: 43/57 (75%) African-American, 45/134 (34%) Hispanic, and 14/103 (14%) Caucasian mothers were vitamin D deficient, 218 women (78.7%) had a baseline 25(OH)D <32 ng/mL, and thus, were either deficient or with marginal vitamin D status. Vitamin D status during pregnancy has implications for lactating women and their infants, especially in light of the significant rise in nutritional rickets in breastfed infants, mainly in the African-American population. The deficiency state is created by limited sun exposure in mother and infant and the minimal contribution of dietary supplementation at the current adequate intake of 200 IU vitamin D/day in the mother.

Supplementing lactating mothers with 2,000 and 4,000 IU vitamin D2/day for a period of three months demonstrated a rise in circulating maternal 25(OH)D. 400 IU/day maternal supplement was ineffective in sustaining the nutritional vitamin D status of the mother or her nursing infant. Mothers given 6,400 IU vitamin D3/day had increased circulating 25(OH)D and 10-fold increase in milk levels which supplied the nursing infant with ample vitamin D to increase and sustain circulating 25(OH)D. While the safety and efficacy of high-dose maternal supplementation during pregnancy and lactation is not confirmed, screening for vitamin D deficiency especially in high risk groups is advised, with recommendations for oral supplementation of vitamin D3, when indicated. The oral doses required to meet these demands are a magnitude higher than current recommendations.