Randomized controlled trial (RCT) of vitamin D supplementation in pregnancy in a population with endemic vitamin D deficiency.

Study answer

What this study found

Vitamin D3 at 4000 IU/day was the most effective dose and was reported as safe, with 2000 IU/day also improving vitamin D status versus 400 IU/day. Mean serum 25(OH)D concentrations at delivery and in cord blood were significantly higher in the 2000 and 4000 IU/day groups than in the 400 IU/day group (p<0.001), and the 4000 IU/day group produced the highest levels. At delivery, 65% of mothers on 4000 IU/day were vitamin D sufficient compared with less than 10% on 400 IU/day; if a 25(OH)D threshold of >20 ng/ml was used, 91% of mothers on 4000 IU/day achieved it, and their infants were four…

Study & population

Double-blind randomized controlled trial in pregnant Arab women in Al Ain, United Arab Emirates, with singleton pregnancies and very high baseline vitamin D deficiency.

Intervention

Pregnant participants were randomized to daily oral vitamin D3 tablets plus standard prenatal vitamins, for a total vitamin D3 intake of either 400 IU/day, 2000 IU/day, or 4000 IU/day.

Key limitation

The trial was relatively small, single-region, and had attrition, with 30 participants discontinuing and only 126 mothers having serum 25(OH)D available at delivery.

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Original abstract