Aim: The literature reports conflicting findings regarding therole of vitamin D in female fertility and assisted reproductivetechniques. In this context, the present study aimed toevaluate the potential association between baseline serum25-hydroxyvitamin D (25-OH vitamin D) levels and pregnancyoutcomes in infertile patients undergoing frozen embryotransfer (FET).Material and Method: In this retrospective study conductedat the Center for Assisted Reproductive Techniques, KocaeliUniversity Faculty of Medicine Hospital, a total of 276 infertilewomen scheduled for FET were screened. Among thesepatients, 92 women with available baseline serum 25-OHvitamin D measurements and complete pregnancy outcomedata were included in the final analysis.Results: When patients with serum 25-OH vitamin D levels <20ng/mL (Group 1, n=48) were compared with those with levels≥20 ng/mL (Group 2, n=44), demographic characteristics weresimilar between the groups. Serum Anti-Mullerian hormone(AMH) levels were significantly higher in Group 1 comparedto Group 2 (p=0.014). There were no statistically significantdifferences between the groups in terms of pregnancy rate(41.6% vs 31.8%; p=0.328), clinical pregnancy rate (35.4%vs 25%; p=0.278), ongoing pregnancy rate (25% vs 18.2%;p=0.428), live birth rate (20.8% vs 18.2%; p=0.749), pregnancyloss rate (18.8% vs 13.6%; p=0.507), or twin pregnancy rate(4.2% vs 9.1%; p=0.421).Conclusion: No statistically significant association wasobserved between pregnancy outcomes following frozenembryo transfer and baseline serum 25-OH vitamin D levelsmeasured at the start of treatment. These findings suggestthat, within the scope of this study, serum vitamin D levelswere not indirectly associated with fertility through effects onendometrial receptivity or the implantation process.
Köle et al. (2026) studied this question.