Most types of male infertility aren't preventable. However, avoid drug and tobacco use and excessive alcohol consumption, which may contribute to male infertility. Also, high temperatures can affect sperm production and motility. Although this effect is usually temporary, avoid hot tubs and steam baths.

If you're a man who's uncertain about whether you would eventually like to become a father, don't undergo permanent sterilization, such as a vasectomy. Although surgery to reverse this condition is possible, risks are involved that could affect fertility in other ways.

A woman can increase her chances of becoming pregnant in a number of ways:

• Exercise moderately. Regular exercise is important, but if you're exercising so intensely that your periods are infrequent or absent, your fertility may be impaired.
• Avoid weight extremes. Being overweight or underweight can affect your hormone production and cause infertility.
• Avoid alcohol, tobacco and street drugs. These substances may impair your ability to conceive and have a healthy pregnancy. Don't drink alcohol or smoke tobacco. Avoid illegal drugs such as marijuana and cocaine.
• Limit caffeine. Women trying to get pregnant may want to limit caffeine intake to no more than 250 milligrams of caffeine a day (one or two cups of coffee).
• Limit medications. The use of both prescription and nonprescription drugs can decrease your chance of getting pregnant or keeping a pregnancy. Talk with your doctor about any medications you take regularly.
• Men should avoid hot tubs.