What role does FUT2 play in fertility?

The FUT2 variant (secretor status) influences the expression of ABH antigens on mucosal surfaces and in body fluids. Studies indicate a link with vaginal microbiome composition and potentially with fertility. Some research suggests associations with recurrent pregnancy loss or altered immune responses, but the evidence is moderate and not conclusive. Most data come from GWAS or population-based studies, not from randomized controlled trials. FUT2 testing alone is not diagnostic for fertility issues; it may provide clues within a comprehensive microbiome or immune status analysis, but cannot replace clinical evaluation. Caveat: Genetic variants explain only a small fraction of fertility variance; lifestyle, hormonal status, and organic causes are far more relevant. Evidence is rated 'human-moderate' due to reproducible associations but lack of causal confirmation.