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.
While some lucky people may get pregnant almost as soon as they start trying, it takes longer for many couples. One good way of increasing your odds is to chart your fertility cycle; that way, you'll better understand when you have the best chance of becoming pregnant. As you go through your cycle, your body gives you all sorts of clues to indicate when it is going into ovulation. You just need to know how to look for them.
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.