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In a robust multicenter randomized controlled trial involving 876 women with PCOS, high-dose Vitamin D supplementation (4000 IU/day) did not increase the likelihood of a live birth after the first embryo transfer compared to a placebo.
While the primary clinical endpoint was not met, the intervention successfully corrected Vitamin D deficiency, raising mean serum 25-hydroxyvitamin D (25-OHD) levels from approximately 16.5 ng/mL to over 32 ng/mL by the day of the trigger.
