Accumulating evidence from animal and human studies indicates a role for vitamin D in female reproductive physiology, and numerous clinical studies have suggested its potential benefit for various aspects of human reproduction. Anti-Müllerian hormone (AMH) is an ovarian biomarker that plays an important role in folliculogenesis. It is the most sensitive ovarian reserve marker and is widely used clinically in reproductive medicine. While initial studies have suggested that vitamin D may be associated with ovarian reserve markers, including AMH, evidence has been conflicting. Currently, there is considerable debate in the field whether vitamin D has the capacity to influence ovarian reserve, as indicated by the AMH level. The current systematic review aims to evaluate and summarize the available evidence regarding the relationship between vitamin D and AMH. In total, 18 observational studies and 6 interventional studies were included in this systematic review. Cross-sectional studies have reported largely discrepant findings regarding an association between serum vitamin D and AMH levels, which are likely due to the heterogeneity in study populations, as well as the apparently complex relationship that may exist between vitamin D and AMH. However, meta-analysis of interventional studies performed herein that examined the effects of vitamin D supplementation on serum AMH levels indicates a cause-effect relationship between vitamin D and AMH, the direction of which appears to depend on a woman's ovulatory status. Serum AMH was significantly decreased following vitamin D supplementation in polycystic ovarian syndrome (PCOS) women (standardized mean difference (SMD) -0.53, 95% CI -0.91 to -0.15, p < 0.007), while it was significantly increased following vitamin D supplementation in ovulatory women without PCOS (SMD 0.49, 95% CI 0.17 to 0.80, p = 0.003). In conclusion, the results of this systematic review demonstrate that the relationship between vitamin D and AMH is a complex one, and large, randomized trials of vitamin D supplementation focusing on different vitamin D status ranges are necessary to gain more insight into the nature of this relationship and the potential benefit of vitamin D to female reproduction in general.
Keywords: anti-Müllerian hormone (AMH); fertility; ovarian reserve; systematic review; vitamin D.