A randomized controlled trial of vitamin D supplementation in pregnancy: effects on vitamin D status and clinical outcomes (1041.5)

Vitamin D status in pregnancy is associated with health outcomes for mother and infant. The current recommendation for vitamin D intake during pregnancy may be insufficient to raise serum 25‐hydroxyvitamin D (25OHD) to optimal levels. This study evaluated the effect of two treatment regimens on vitamin D status and clinical outcomes. 57 pregnant women at risk for low 25OHD were randomized to treatment (2,000 IU vitamin D3/d) or control (400 IU/d) from <20 wk gestation until delivery. 51 women completed the study. Plasma vitamin D metabolites were measured at <20 wk, 26 wk, and 36 wk gestation. 25OHD was significantly greater in the treatment group at both 26 (104.515.7 vs. 86.320.2 nmol/L) and 36 wk (115.820.1 vs. 85.618.0 nmol/L; p<0.05). The treatment group had a larger change over pregnancy than the control (p<0.0001), and a significantly greater proportion achieved a 25OHD >75 nmol/L by 36 wk (96% vs. 73.1%; p=0.02). Plasma 1,25‐dihydroxyvitamin D increased more in the treatment than the control group between baseline and 26 wk (p<0.01) and 36 wk (p<0.01). Maternal clinical outcomes, including blood pressure and glucose tolerance, did not differ between groups. Infants born to mothers in the treatment group had a marginally (p=0.06) greater birth weight (3,668431 g) than those in the control group (3,379557 g). A daily dose of 2,000 IU is effective at improving vitamin D status in pregnant women. Grant Funding Source : Supported by UC Davis CTSC Vision Grant, UL1 TR2 and USDA‐ARS