The Effects of Vitamin D Levels on Pregnancy Outcomes in Patients Receiving Frozen Embryo Transfer

Aim: The literature reports conflicting findings regarding the
role of vitamin D in female fertility and assisted reproductive
techniques. In this context, the present study aimed to
evaluate the potential association between baseline serum
25-hydroxyvitamin D (25-OH vitamin D) levels and pregnancy
outcomes in infertile patients undergoing frozen embryo
transfer (FET).
Material and Method: In this retrospective study conducted
at the Center for Assisted Reproductive Techniques, Kocaeli
University Faculty of Medicine Hospital, a total of 276 infertile
women scheduled for FET were screened. Among these
patients, 92 women with available baseline serum 25-OH
vitamin D measurements and complete pregnancy outcome
data were included in the final analysis.
Results: When patients with serum 25-OH vitamin D levels <20
ng/mL (Group 1, n=48) were compared with those with levels
≥20 ng/mL (Group 2, n=44), demographic characteristics were
similar between the groups. Serum Anti-Mullerian hormone
(AMH) levels were significantly higher in Group 1 compared
to Group 2 (p=0.014). There were no statistically significant
differences 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), pregnancy
loss 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 was
observed between pregnancy outcomes following frozen
embryo transfer and baseline serum 25-OH vitamin D levels
measured at the start of treatment. These findings suggest
that, within the scope of this study, serum vitamin D levels
were not indirectly associated with fertility through effects on
endometrial receptivity or the implantation process.