A risk factor is something that increases your likelihood of
getting a disease or condition. It is possible to develop
infertility with or without the risk factors listed below.
However, the more risk factors you have, the greater your
likelihood of developing infertility. If you have a number of
risk factors, ask your doctor what you can do to reduce your
risk. Risk factors for infertility in men include: The toxins in
cigarette smoke negatively affect sperm quality. The
concentration of sperm in semen is decreased, sperm motility
(movement) is reduced, and the number of abnormal sperm is
increased. Smoking also has adverse effects on hormone levels
and may affect the cells in the testes that produce
testosterone. Although moderate alcohol consumption does not
affect male fertility, excessive alcohol intake alters hormone
levels and reduces sperm count and sperm quality. Like cigarette
smoking, use of marijuana also can adversely affect sperm count,
sperm motility, and sperm morphology. It also reduces plasm