Abstract
Environmental and lifestyle factors interact with human reproduction and are potentially modifiable. This review addresses the available evidence for the role of cigarette smoking, alcohol use, caffeine use, cocaine use, marijuana use, obesity and circadian rhythm in fertility. Clinical studies in this field have many methodological limitations. Based on current evidence, we advise against cigarette smoking, alcohol use, high caffeine consumption and cocaine use. Overweight and obese women should be encouraged toward weight reduction. Future translational studies will better link circadian rhythm disturbances with human fertility.