What are some possible causes of male infertility?

Men can also contribute to infertility in a couple. In fact, men are found to be the only cause or a contributing cause of infertility problems in couples in about 40% of cases.1

To conceive a child, a male's sperm must combine with a female's egg. The testicles make and store sperm, which are ejaculated by the penis to deliver sperm to the female reproductive tract during sexual intercourse.

The most common issues that lead to infertility in men are problems that affect how the testicles work. Other problems are hormone imbalances or blockages or absence of some of the ducts in the male reproductive organs.2Lifestyle factors and age-related factors also play a role in male infertility.

A complete lack of sperm is the cause of infertility in about 15% of men who are infertile. When a man does not produce sperm, it is called azoospermia (pronounced ay-zoh-uh-SPUR-mee-uh). A hormone imbalance or a blockage of sperm movement can cause azoospermia.3

In some cases of infertility, a man produces less sperm than normal. This condition is called oligospermia (pronounced OL-ih-goh-SPUR-mee-uh) or a low sperm count. The most common cause of oligospermia is varicocele (pronounced VAR-ih-koh-seel), an enlarged vein in the testicle.

Many different issues can affect the formation of sperm in the testicles. These conditions can lead to sperm that is abnormally shaped or malformed or to low amounts of sperm. Some of the more common issues include:4

  • Chromosome defects
  • Diabetes
  • Hyperprolactinemia (pronounced hi-purr-proh-lak-tih-NEE-mee-ah), which is overproduction of a hormone called prolactin made by the pituitary gland
  • Injury to the testicle
  • Insensitivity to hormones called androgens, which include testosterone
  • Swelling of the testicles from infections such as mumps, gonorrhea, or chlamydia
  • Chromosome disorder called Klinefelter syndrome
  • Thyroid problems
  • Cryptorchidism (pronounced krip-TAWR-ki-diz-uhm), which occurs when one or both testicles are not descended
  • Varicocele, which is the enlargement of veins in the scrotum; enlarged veins disrupt the blood flow in the testicle and cause an increase in temperature, which negatively affects sperm production. This condition is present in about 40% of men with fertility problems.5

Remember that lifestyle, environmental, and age-related factors can also play a role in male infertility.

Even if the male's body produces enough viable sperm, sometimes factors and conditions that affect how or whether the sperm moves can also contribute to infertility. Sperm may move too slowly or not at all and thus die before they can reach the egg. Sometimes the seminal fluid, which contains the sperm, is too thick for the sperm to move around properly.

An inability to transport sperm from the testicles to the penis causes about 10% to 20% of the cases of male infertility.2 The inability can be caused by natural blockages in the tubes that transport sperm from the testicles to the penis or from vasectomy, a surgical procedure that cuts and seals the ends of the tubes.

Many men with cystic fibrosis lack the tubes that carry the sperm out of the testicles, making them infertile (but not sterile, because they produce sperm).

Some men have problems getting an erection, called erectile dysfunction, which makes having sex difficult.

A condition called retrograde ejaculation can also cause infertility. This condition causes sperm to move into the bladder instead of out of the penis. Some medications increase the likelihood of this problem.


  1. American Society for Reproductive Medicine. (n.d.). Quick facts about infertility. Retrieved May 31, 2016, from http://connect.asrm.org/srs/about/new-item9?ssopc=1 external link
  2. Jose-Miller, A. B., Boyden, J. W., & Frey, K. A. (2007). Infertility. American Family Physician, 75, 849–856.
  3. Jarow, J., Sigman, M., Kolettis, P., Lipshultz, L. R., McClure, D., Nangia, A. K., et al. (2011). The evaluation of the azoospermic male: Best practice statement reviewed and revised 2011. American Urological Association. Retrieved May 31, 2016, from https://www.auanet.org/guidelines-and-quality/guidelines/male-infertility external link
  4. Lindsay, T. J., & Vitrikas, K. R. (2015). Evaluation and treatment of infertility. American Family Physician, 91(5), 308–314.
  5. American Society for Reproductive Medicine & Society for Male Reproduction and Urology. (2014). Report on varicocele and infertility: A committee opinion.Fertility and Sterility,102, 1556–1560.
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