Causes of Male Factor Infertility

The most common cause of male factor infertility is low sperm count. Absence of sperm in the semen is less common, affecting only 1 percent of all men and 10 to 15 percent of infertile men. A semen analysis can determine whether male infertility is caused by a low or absent sperm count.
Potential causes of sperm count problems include the following:

• Hormonal problems of the testicles or pituitary gland
• Testicular injury or failure, either present at birth (congenital) or associated with radiation or toxic chemical exposure
• Cancer treatment with certain kinds of chemotherapy or radiation
• Antibodies that attack sperm (sperm antibodies sometimes develop in a man’s semen when his sperm has been exposed to his immune system outside of the testicles. This may happen after a vasectomy, an infection, or an injury to the testicles.)
• Drug use (including some prescription medications, as well as marijuana, tobacco, and alcohol)
• Structural problems, such as:
  • A varicocele in the testicles
  • Blocked ejaculation due to a surgical vasectomy
  • Absence of a vas deferens (a birth defect that may be associated with the cystic fibrosis gene)
  • Retrograde ejaculation (the ejaculation of semen into the bladder rather than out through the penis)
• Chromosomal problems (such as Klinefelter syndrome)
• Genetic problems

Other factors that may cause male infertility include:

• Excessive exercise (Studies have shown that exercising too much may lead to the release of high amounts of steroid hormones)
• Stress
• Obesity
• Heat (from tight clothing, frequent bike riding, hot baths, or saunas)
• Exposure to toxins and environmental hazards (e.g. pesticides, lead, radiation, radioactive substances, mercury, and heavy metals)