Association of lower serum and follicular fluid vitamin D levels with reduced fertilization rates in IVF patients with diminished ovarian reserve.

INTRODUCTION

This study aimed to investigate the association between 25-hydroxyvitamin D [25(OH)D] levels in serum (VD-S) and follicular fluid (VD-FF) and the laboratory outcomes of in vitro fertilization (IVF) in patients with diminished ovarian reserve (DOR).

METHODS

This prospective cohort study enrolled 145 women undergoing IVF, comprising 74 patients with DOR and 71 with normal ovarian reserve (NOR) as controls. VD-S and VD-FF levels were measured. The DOR group was further stratified into vitamin D (VD) non-deficient (VDH) and VD deficient (VDL) subgroups. Baseline characteristics and IVF laboratory outcomes were compared between the groups and subgroups.

RESULTS

A significant positive correlation was observed between VD-S and VD-FF levels (r = 0.769, P < 0.001). Patients in the DOR group had significantly lower 25(OH)D levels in both serum (P = 0.048) and follicular fluid (P = 0.015) compared to the NOR group. Within the DOR cohort, the VDH subgroup demonstrated significantly higher oocyte retrieval rates (95.0% vs. 84.6%, P = 0.021) and normal fertilization rates (72.9% vs. 56.3%, P = 0.016) than the VDL subgroup when stratified by VD-S. Similar results were found when stratifying by follicular fluid levels. Furthermore, the VDH subgroup exhibited significantly higher high-density lipoprotein (HDL) levels (P < 0.05).

CONCLUSION

In patients with diminished ovarian reserve, higher 25(OH)D levels in serum and follicular fluid are positively associated with higher oocyte retrieval and normal fertilization rates during IVF cycles. These findings suggest that VD deficiency may be a modifiable factor associated with IVF outcomes in this specific population.