Randomized trial of three doses of vitamin D to reduce deficiency in pregnant Mongolian women.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 30552064 · doi:10.1016/j.ebiom.2018.11.060
What was done
A randomized, double-blind controlled trial in Mongolia evaluated three daily doses of vitamin D3 in pregnant women starting at 12–16 weeks' gestation: 600 IU (n = 119), 2000 IU (n = 121), and 4000 IU (n = 120). Serum 25-hydroxyvitamin D [25(OH)D] was measured using an enzyme-linked fluorescent assay at baseline, at 36–40 weeks' gestation, and in umbilical cord blood.
What was found
At baseline, mean ± standard deviation 25(OH)D concentration was 19 ± 22 nmol/l, and 91% were <50 nmol/l. At 36–40 weeks, maternal 25(OH)D concentrations rose to 46 ± 21 nmol/l with 600 IU, 70 ± 23 nmol/l with 2000 IU, and 81 ± 29 nmol/l with 4000 IU (p < 0.0001 across arms; p = 0.002 for 2000 vs. 4000 IU). Umbilical cord blood concentrations mirrored maternal levels (p < 0.0001 across arms; p < 0.0001 for 2000 vs. 4000 IU). High adherence was observed (88% took ≥80% of supplements), and no adverse events, including hypercalcemia, were attributed to supplementation.
Why it matters
Standard prenatal dosing of 600 IU/day was insufficient to correct vitamin D deficiency in this high-risk population, whereas 4000 IU/day safely achieved the highest maternal and neonatal 25(OH)D levels.
Limits
The study was conducted in a single geographic setting with high baseline winter deficiency, which may limit generalizability to baseline-replete populations. The abstract does not report clinical maternal or infant health outcomes, focusing entirely on biochemical 25(OH)D levels and safety endpoints.
Cited by
- supports Supplementation with approximately 4,000 IU of vitamin D per day can raise deficient individuals to sufficient levels above 30 or 40 ng/mL.