Key finding
330 pregnant women in Lebanon with low vitamin D (25(OH)D 10 to 30 ng/mL) joined before 18 weeks. They took either 20,000 IU of vitamin D3 a week (about 2,857 IU a day) or 10,000 IU every 2 weeks (about 714 IU a day). At delivery, every mother on the higher dose had a level of at least 20 ng/mL, compared with 85% on the lower dose. In cord blood, 77% of babies reached that level on the higher dose, against about 40% on the lower dose. Baby bone mass did not differ significantly, and no vitamin D toxicity or raised blood calcium was attributed to supplementation.
In pregnant women with low vitamin D, a dose of around 400 to 600 IU a day may not be enough to bring mother and baby up to sufficient levels. A higher weekly vitamin D3 dose under supervision is worth considering. The trial looked at blood levels and bone measures, not at outcomes such as pre-eclampsia.
Chakhtoura M, Nassar AH, Ajjour S, Rahme M, Assaad M, Nabulsi M, Charafeddine L, Mahfoud ZR, Tfaily N, Diab T, Al-Tayeh R, Zeitoun A, Shepherd JA, Cavalier E, Cooper C, Harvey N, Eid J, Chlela M, El-Hajj Fuleihan G. Maternal and neonatal outcomes of vitamin D supplementation in hypovitaminosis D pregnancy: preg-D randomized trial. J Clin Endocrinol Metab. 2026; dgag245.
Read the original paperSummarised by the Draxer Clinical Advisory Department for health professionals. It supports, and does not replace, clinical judgement.