The Impact of Chlamydia trachomatis on Male Infertility: A Systematic Review and Meta-Analysis.

Background: Chlamydia trachomatis (CT) is a common sexually transmitted infection, yet its contribution to male infertility remains incompletely understood. Methods: A systematic review and meta-analysis of case-control studies were conducted following PRISMA guidelines. Literature from PubMed/MEDLINE, Scopus, Cochrane, and Embase (2000 onward) was screened. Random-effects models were used in R, with subgroup analyses by geography, case definition, diagnostics, and matching criteria. Results: Out of 2941 records, 26 case-control studies (11 706 participants) met inclusion criteria. Most studies used molecular diagnostics (n = 23). A significant association was found between CT infection and male infertility (odds ratio [OR] 3.68 [95% CI 2.24-6.02]), with substantial heterogeneity (I 2 = 65%). Age-matched studies showed higher effect sizes (OR 6.77), and publication bias was detected (trimmed OR 2.75). Conclusions: While findings suggest that CT infection may impair male fertility, confounding, bias, and the lack of geographical representativeness limit inference. High-quality, large-scale prospective studies are needed to confirm causality and guide targeted interventions.