Reproductive health refers to the diseases, disorders and conditions that affect the functioning of the male and female reproductive systems during all stages of life. Disorders of reproduction include birth defects, developmental disorders, low birth weight, preterm birth, reduced fertility, impotence, and menstrual disorders. Research has shown that exposure to environmental pollutants may pose the greatest threat to reproductive health. Exposure to lead is associated with reduced fertility in both men and women, while mercury exposure has been linked to birth defects and neurological disorders. A growing body of evidence suggests that exposure to endocrine disruptors, chemicals that appear to disrupt hormonal activity in humans and animals, may contribute to problems with fertility, pregnancy, and other aspects of reproduction.