Infertility is not always a woman’s problem, men can also have problems that cause infertility. About 1/3 of infertility cases are caused by women’s problems, another 1/3 are due to the man, and the rest are caused by a mixture of male and female problems or by unknown problems.
Infertility in men is most often caused by:
- A problem called varicocele (VAIR-ih-koh-seel). This is when the veins on a man’s testicle(s) are too large, which heats the testicles. The heat can affect the number or shape of the sperm.
- Other factors that can cause a man to make too few sperm or none at all.
- Movement of the sperm. This may be caused by the shape of the sperm. Sometimes injuries or other damage to the reproductive system block the sperm.
A man’s sperm can be changed by this overall health and lifestyle. Some things that may reduce the health or number of sperm include:
- Heavy alcohol use
- Drugs
- Smoking cigarettes
- Age
- Environmental toxins, including pesticides and lead
- Health problems such as mumps, serious conditions like kidney disease, or hormone problems
- Medicines
- Radiation treatment and chemotherapy for cancer
Sometimes a man is born with the problems that affect his sperm. Other times problems start later in life due to illness of injury. For example, cystic fibrosis often causes infertility in men.