Toxic effects related to tobacco, marijuana, and other drugs
Smoking may cause infertility in both men and women. In experimental animals, nicotine has been shown to block the production of sperm and decrease the size of male testicles. In women, tobacco changes the cervical mucus, thus affecting the way sperm reach the egg.
Marijuana may disrupt a woman's ovulation cycle, affecting the release of the egg. In men, marijuana use can decrease the sperm count as well as affect the quality of the sperm.
Heroin, cocaine, and crack cocaine use induces similar effects but places the user at increased risk for PID and HIV infection associated with risky sexual behavior.
Exercise should be encouraged for both women and men who are gearing up to try to conceive. However, excessive, strenuous exercise in women may result in disruption of the ovulation cycle, thereby affecting her periods. Normal exercise has not been linked to miscarriages (loss of pregnancy), but certain forms of exercise (for example, high-impact or contact sports or scuba diving) should be avoided in pregnancy. In men, too much exercise may cause a low sperm count.
In women, the effects of alcohol are related to severe consequences for the fetus. And chronic alcoholism is related to disorders in ovulation, which interferes with fertility. Alcohol use by men interferes with the synthesis of testosterone and has an impact on sperm concentration. Alcoholism may delay a man's sexual response and cause impotence by interfering with a man's ability to have an erection.