Vitamin D supplementation in human pregnancy

Abstract

Vitamin D deficiency is a prevalent problem worldwide and data suggest that maternal vitamin D deficiency is associated with adverse maternal and offspring non-skeletal outcomes. We performed a double-blind randomised controlled trial to establish the effect of high-dose (5000 IU) vitamin D supplementation on glucose metabolism measured by the 75g oral glucose tolerance test (OGTT) and insulin resistance on the homeostasis model assessment (HOMA-IR). Additionally, we evaluated the vitamin D status of a multiethnic pregnant population and determined the predictive factors for vitamin D deficiency. Finally, we determined the association between maternal vitamin D status and intrauterine and neonatal growth, and the effects of high-dose vitamin D supplementation on the same parameters. We identified that low maternal vitamin D status at baseline was associated with more adverse glucose tolerance on the OGTT. High-dose vitamin D supplementation improved maternal and infant 25-hydroxyvitamin D (25OHD) but did not improve glucose levels and HOMA-IR. Nearly half of our cohort had 25OHD<50nmol/L. Ethnicity, Δ skin reflectance and vitamin D containing pregnancy multivitamin use predicted baseline vitamin D status. Maternal vitamin D status during pregnancy was not associated with intrauterine growth and high-dose vitamin D supplementation did not affect intrauterine or birth measures.