Work

Association of heavy metal with sperm parameters and sex hormones: A systematic review and meta-analysis of observational studies

Year: 2026

Type: review

Study designs: Systematic Review, Meta-Analysis

Abstract: Background: Findings regarding the reproductive toxicity effect of heavy metals on sperm parameters and sex hormones level remain inconsistent. This study systematically reviewed and pooled the existing literature to assess the associations of heavy metal levels with sperm parameters and sex hormones. Methods: In this systematic review, international databases including PubMed, Scopus, and Web of Science were searched until 31 March 2025 according to PRISMA guidelines. Observational studies assessing heavy metal concentrations in biological samples and their associations with sperm parameters or sex hormone levels were included. The chi-square-based Q test and I-squared statistics were used to assess the heterogeneity, and pooled estimates were obtained using a random-effects meta-analysis model. Results: Eighteen studies involving 4041 participants were included. Qualitative synthesis revealed heterogeneous findings across heavy metals and sperm parameters, with significant findings reported mainly for Cd and Pb, while most associations with reproductive hormones were non-significant. Meta-analysis demonstrated a significant inverse association between seminal Cd and sperm motility (pooled Fisher's z = -0.17, 95% CI: -0.30 to -0.04; I² = 0%), whereas no significant pooled associations were observed for seminal Pb. Conclusions: The current evidence does not demonstrate consistent associations between heavy metal exposure and male reproductive parameters; however, limited significant inverse correlations were identified between seminal Cd and sperm motility. Evidence regarding reproductive hormones was limited and largely inconclusive, highlighting the need for larger, well-designed prospective studies.

Source: European Journal of Obstetrics & Gynecology and Reproductive Biology X

DOI: 10.1016/j.eurox.2026.100505