Summary: In a large multicentre trial in women with polycystic ovary syndrome undergoing IVF, vitamin D 4000 IU daily for up to 90 days raised serum 25-hydroxyvitamin D but did not improve live birth rates after the first embryo transfer.
PICO Summary
| Element | Detail |
|---|---|
| Population | 876 women with polycystic ovary syndrome undergoing IVF across 24 fertility centres in China (865 analysed). |
| Intervention | Vitamin D 4000 IU/day for up to 90 days before IVF (n=435). |
| Comparison | Placebo (n=430). |
| Outcome | Trigger-day 25-OHD higher with vitamin D (32.3 vs 18.2 ng/mL; adjusted difference 13.6; 95% CI 10.9–16.3). Live birth after first transfer 52.0% vs 50.2% (adjusted risk ratio 1.03; 95% CI 0.91–1.18). Severe ovarian hyperstimulation syndrome in 3 vs 6. |
Vitamin D before IVF in PCOS
RCT · PCOS · up to 90 days
Vitamin D raised serum 25-OHD but did not improve live birth after the first embryo transfer in women with PCOS undergoing IVF.
Expert Commentary
Vitamin D is endlessly proposed as a fix for PCOS-related subfertility on the back of observational associations, so a large, multicentre, double-blind trial with the outcome that actually matters, live birth, is exactly what the question deserved. The result is cleanly negative, and I find it convincing: the supplement did what supplements do, it raised serum 25-OHD substantially, but the live birth rate was essentially identical at around 51% in both arms, with a risk ratio sitting on 1.0 and a tight confidence interval. This is the recurring lesson of the vitamin D literature, that correcting a blood level is not the same as changing a clinical outcome. The trial is well powered and well conducted, and the population was mildly deficient at baseline, so this is not explained away by everyone being replete. Can I use this with my patients? Yes, as clear counselling: I will not recommend vitamin D to women with PCOS specifically to improve their IVF success, because it does not. I would still correct documented deficiency for general health reasons, but I would not let anyone delay or pin fertility hopes on it.
References
Hu KL, Liao T, Wu Q, et al. Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial. BMJ. 2026;392:e087438. doi:10.1136/bmj-2025-087438