Lifestyle factors and male infertility: an evidence-based review

Human semen is the end result of a sophisticated biological process that is hormonally regulated, produced by highly specialized cellular lines that differentiate in embryo, initiate division at puberty and continue dividing throughout the man’s entire life span in 72-day cycles. Semen is a sensitive indicator of environmental, occupational and lifestyle exposures that can exert direct toxic effects and hormonal disruption. Damage may occur at any stage of life. However, while some exposures may produce reversible changes, others, especially damage to germinal cells in utero or prepuberty, may result in permanent sequelae. We review the main factors that affect human male fertility and their possible influence on human reproduction. Some lifestyles, xenoestrogens, heavy metals and volatile organic compounds are already known to compromise male reproductive function. Nonetheless, many questions remain, and we still know little about the effect of many other factors on male fertility.