Experimental animal models have suggested an adverse link between scrotal temperature and impaired spermatogenesis. One study did identify a lower average sperm concentration in men who had a higher scrotal temperature, however, the actual value still fell within the WHO’s normal range. There is limited evidence that testicular cooling might improve semen quality.
Found abundantly, endocrine disruptors mimic natural hormones and have been shown to have a detrimental effect on both male and female fertility. Some of the most widely studied examples are bisphenol A (BPA) and phthalates, which are both used in the manufacture of plastics.
Alcohol, psychological stress and caffeine are alternative factors that have been associated with impaired fertility.