The level of vitamin D in follicular fluid and ovarian reserve in an in vitro fertilization program: A pilot study

Background: The level of vitamin D in follicular fluid (FF) according to the ovarian reserve has never been investigated, and the effect of FF vitamin D on the outcome of assisted reproductive technology (ART) remains controversial. The aim of this study is to evaluate the association between FF vitamin D levels and baseline anti-Müllerian hormone (AMH) / ART outcomes. Methods: Forty-seven patients who underwent controlled ovarian stimulation at the fertility clinic of an academic tertiary care center were enrolled for a prospective observational study. FF was collected from the first aspirated leading follicle of each ovary and assayed by an enzyme-linked immunosorbent assay. Multivariable linear regression analysis was used to assess the association between baseline AMH and FF vitamin D levels with adjustment for basal FSH and serum vitamin D levels. Results: Both the AMH and serum vitamin D were significant predictors for FF vitamin D. The estimated marginal mean of FF vitamin D level was higher in women with decreased ovarian reserve (DOR) than those with normal ovarian reserve (24.1 ± 2.1 vs. 18.8 ± 1.4 ng/ml, p = 0.048). However, FF vitamin D did not demonstrate any significant associations with cycle outcomes, including fertilization rate and the number and proportion of good embryos at day three. Conclusion: We observed significantly higher FF vitamin D levels in women with DOR. However, FF vitamin D did not demonstrate any significant associations with the outcome of ART. A larger prospective study is needed to investigate the effect of FF vitamin D on the clinical pregnancy rate and live birth rate.