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 a man's testicles. In women, tobacco changes the cervical mucus, thus affecting the way sperm reach the egg. It also increases the risk of an ectopic pregnancy by affecting the fallopian tubes.
Marijuana may disrupt a woman's ovulation cycle (release of the egg). Marijuana use affects men by decreasing the sperm count and the quality of the sperm.
Irregular or abnormal ovulation accounts for 30% to 40% of all cases of infertility. Having irregular periods, no periods, or abnormal bleeding often indicates that you aren't ovulating, a condition known clinically as anovulation.
Although anovulation can usually be treated with fertility drugs, it is important to be evaluated for other conditions that could interfere with ovulation, such as thyroid conditions or abnormalities of the adrenal or pituitary glands.
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.
In women, the effects of alcohol are related more to severe consequences for the fetus. Nevertheless, chronic alcoholism is related to disorders in ovulation and, therefore, 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 may cause impotence, the inability to have or sustain an erection.