Exposure to mercury and human reproductive health: A systematic review

•Increased mercury levels were associated with infertility or subfertility status.•Infertile males had higher levels of mercury in hair than fertile males.•Mercury reduced semen quality parameters.•Increased mercury levels were associated with incidence of menstrual and hormonal disorders. Evidences from human and animal studies suggest that reproductive function may be affected by mercury. The aim of this review was to explore the mercury influence on human fertility. A systematic search was made in PubMED for papers published between 1975–2017, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Increased mercury levels were associated with infertility or subfertility status. Further, infertile subjects with unexplained infertility showed higher levels of mercury in hair, blood and urine than fertile ones. Mercury exposure induced sperm DNA damage and abnormal sperm morphology and motility. Additionally, mercury levels were related with higher incidence of menstrual and hormonal disorders and increased rates of adverse reproductive outcomes. Our review showed that mercury negatively impacts human reproduction, affecting the reproductive and endocrine systems in both male and female. However, the molecular mechanisms underlying the mercury-associated decline on fertility remains unknown.