Infertility in Men - Sperm Abnormalities

Risk Factors

Varicocele

A varicocele is an abnormally enlarged and twisted (varicose) vein in the spermatic cord that connects to the testicle. Varicoceles are found in about 15% of all men and in about 40% of infertile men, although it is not clear how much they affect fertility or by what mechanisms. They can raise testicular temperature, which may have effects on sperm production, movement, and shape.

Click the icon to see an image of a varicocele.

Age

Age-related sperm changes in men are not abrupt, but are a gradual process. Aging can adversely affect sperm counts and sperm motility (the sperm's ability to swim quickly and move in a straight line). The genetic quality of sperm declines as a man ages.

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Sexually Transmitted Diseases

Repeated Chlamydia trachomatis or gonorrhea infections are the sexually transmitted diseases most often associated with male infertility. Such infections can cause scarring and block sperm passage. Human papillomaviruses, the cause of genital warts, may also impair sperm function.

Lifestyle Factors

Nearly any major physical or mental stress can temporarily reduce sperm count. Some common conditions that lower sperm count, temporarily in nearly all cases, include:

Emotional Stress. Stress may interfere with certain hormones involved with sperm production.

Testicular Overheating. Overheating, such as from high fevers, saunas, and hot tubs, may temporarily lower sperm count.

Substance Abuse. Cocaine or heavy marijuana use can temporarily reduce the number and quality of sperm. Chemical compounds in marijuana may impair sperms' ability to swim and also inhibit their ability to penetrate the egg. Anabolic steroid use can shrink testicles and decrease sperm production. Heavy drinking may also impair fertility.

Smoking. Cigarette smoking may affect sperm quality.

Obesity. Obesity may impair hormonal levels and adversely affect fertility.

Bicycling. Bicycling may affect erectile function. Pressure from the bike seat may damage blood vessels and nerves that are responsible for erections. Mountain biking, which involves riding on off-road terrain, exposes the perineum (the region between the scrotum and the anus) to more extreme shocks and vibrations and increases the risk for injuries to the scrotum. A padded or contoured bike seat set at the proper height and angle can help reduce this risk.