NCT00011713.

. This association persisted when analyses were restricted to women with serum 25(OH)D between 50 and 125 nmol/L when models were further adjusted for season of blood draw and when analyses were restricted to the first treatment cycle. However, 25(OH)D concentrations were unrelated to probability of pregnancy (P-trend = 0.83) or live birth after ART (P-trend = 0.47). Conclusion: Vitamin D may be associated with higher fertilization rates, but this apparent benefit does not translate into higher probability of pregnancy or live birth. This trial was registered at www.clinicaltrials.gov as NCT00011713.Am J Clin Nutr 2016;104:729-35.