This prospective cohort study of 400 lead exposed and 400 non-lead exposed women and their husbands assesses endocrine dysfunction and adverse reproductive outcomes. Residing in two study areas in Shenyang, China, the women are married, 20 and 34 years of age, never smokers, have obtained permission to have a child, and have attempted to become pregnant over the course of the study. Lead exposure is defined by lead levels in blood samples collected at the baseline survey (both women and their husbands), first and second trimesters, and at delivery (both maternal and cord blood). Endocrine dysfunction is monitored by urinary hormone metabolites including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrone conjugates (E1C), and pregnanediol-3-glucuronide (PdG). Reproductive endpoints include menstrual disturbance, time to conception, spontaneous abortion, preterm delivery, and low birth weight.