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What Causes Low Sperm Count?

What Causes Low Sperm Count?

Around half of the infertility problems encountered by couples are caused by male infertility. The most common form of male infertility is a low sperm count.

“Normal” sperm count, as defined by the World Health Organization, is characterized by:

  • The concentration of spermatozoa should be at least 20 million per ml.
  • The total volume of semen should be at least 2ml.
  • The total number of spermatozoa in the ejaculate should be at least 40 million.
  • At least 75 per cent of the spermatozoa should be alive (it is normal for up to 25 per cent to be dead).
  • At least 30 per cent of the spermatozoa should be of normal shape and form.
  • At least 25 per cent of the spermatozoa should be swimming with rapid forward movement.
  • At least 50 per cent of the spermatozoa should be swimming forward, even if only sluggishly.

When a man’s sperm count is below these figures, he has a low sperm count. There are several factors that can cause a low sperm count, including:

  • Genetic causes. These can include Cystic Fibrosis patients who often are missing or have obstructed vas deferens (the tube that carries sperm.) Men who have Klinefelter system, in which they carry two X and one Y chromosome, may negatively impact the testicles and cause infertility. Kartagener syndrome, which is a disorder in which the position of the major organs are reversed, can also cause infertility.
  • Stress may reduce sperm count by interfering with hormones.
  • Sexual technique. Sometimes, a problem with sexual intercourse or technique may affect fertility. Premature ejaculation may also prevent fertility. Incorrect use of lubricants may also affect fertility.
  • Testicular overheating. Overheating of the testicles, such as occurs with fever or the use of a sauna or hot tub may impair fertility.
  • The use of prescription or illicit drugs may affect fertility.
  • Some studies suggest that smoking cigarettes may impair sperm count, reduce sperm lifespan, and lead to lower sex drive.
  • Deficiencies in some nutrients, such as selenium, zinc, foliate and Vitamin C may be risk factors for low sperm count.
  • Some studies suggest an association between obesity and low sperm count.
  • Bicycling may damage blood vessels and nerves that are responsible for erections, and the vibrations and shocks associated with bicycling may increase the risk of injuries to the scrotum.
  • Exposure to toxins, chemicals, and heavy metals such as lead or cadmium may cause low sperm count.
  • A varicocele, which is a varicose vein in the cord that connects to the testicle, may impact fertility.
  • Infections can also affect fertility.

Last modified: February 10, 2013


The information provided here should not be considered medical advice. It is based on the average experience of women trying to conceive and may not be what you may be experiencing. It's not meant to be a replacement for any advice you may receive from your doctor. If you have any concerns about your cycle or our ability to get pregnant, we advise you to contact your doctor.