Abstract:

Folates are important B9 vitamins that are believed to have a crucial role in female reproduction. Folates are required for one-carbon biosynthetic and epigenetic processes that facilitate the synthesis and methylation of nucleic acids and proteins. Folates are thus needed during periods of rapid cell growth and proliferation, which occur in follicular development in the ovaries, and subsequent pregnancy establishment and embryo development. Insufficient folate intake has been shown to impair female fertility and early pregnancy in different studies, emphasizing the necessity of folate during mammalian folliculogenesis and pregnancy establishment. In the in vitro fertilization procedure, the most successful infertility treatment, folate-deficient women have shown impaired ovarian function, lower oocyte quality and pregnancy rates. Dietary or genetically determined folate deficiency may impair the folate-metabolizing pathway, leading to altered DNA methylation and disrupted DNA integrity, and increased blood homocysteine levels. Elevated follicular fluid homocysteine levels correlate with poor oocyte maturity, reduced fertilization rates and poor in vitro embryo quality, while methylenetetrahydrofolate reductase gene polymorphisms are associated with lower ovarian follicular reserve, diminished response to ovarian stimulation, and reduced chance of live birth after in vitro fertilization. Previous studies emphasize that imbalances in folate metabolism and related gene variants may impair female fertility and affect embryo implantation and successful pregnancy establishment.