Regimens of vitamin D supplementation for women during pregnancy.
Maria Angelica Trak-Fellermeier, Ximena E Palma Molina, Samantha L Huey et al.
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In 30 seconds
This updated Cochrane systematic review and meta-analysis assessed randomised trials of vitamin D regimens during pregnancy in women without pre-existing conditions or multiple pregnancies. It included 25 studies involving 7008 women. Compared with doses up to 600 IU/day, doses above 600 IU/day may make little or no difference to pre-eclampsia (RR 0.90, 95% CI 0.65 to 1.25); the review likewise found little or no difference for gestational diabetes, preterm birth, or low birthweight. Evidence certainty was low for most critical outcomes, limiting confidence in these comparisons.
Key findings
- Above 600 IU/day versus up to 600 IU/day: pre-eclampsia risk RR 0.90, 95% CI 0.65 to 1.25; low-certainty evidence.
- Above 600 IU/day versus up to 600 IU/day: gestational diabetes RR 0.85, 95% CI 0.52 to 1.40; low-certainty evidence.
- Above 600 IU/day versus up to 600 IU/day: preterm birth RR 1.02, 95% CI 0.78 to 1.32; low-certainty evidence.
- Above 600 IU/day versus up to 600 IU/day: low birthweight RR 0.90, 95% CI 0.71 to 1.14; low-certainty evidence.
Why it matters
Vitamin D supplementation is used during pregnancy, but the benefits of different doses for important maternal and infant outcomes remain uncertain. These pooled trial findings do not show a clear advantage for higher-dose regimens across the reported outcomes. The low certainty of the evidence means that apparent lack of difference should not be interpreted as proof that doses are equivalent.
What to keep in mind
Evidence certainty was low for most critical outcomes, reflecting serious risk of bias and imprecision. The abstract does not provide results for the comparison of 4000 IU/day or more versus less than 4000 IU/day beyond pre-eclampsia and gestational diabetes.