What is oligospermia?

Oligospermia refers to a low sperm quantity in the ejaculated semen. It is an sperm alteration characterized by a reduced concentration of sperm, which can affect, or make impossible, the achievement of the pregnancy in a natural way.

This disease, also known as low sperm count or oligozoospermia, can occur if the sperm concentration values are under 15 million sperm per millimeter, according to the reference values established by the World Health Organization (WHO). Its definition can be considered polemic, because oligospermia was previously considered whenever the values were under 20 million sperm per millimeter.

The quantity of 15 million sperm per millimeter is a reference since 2010, when the World Health Organization changed the values of sperm parameters of what was considered normospermia, which means minimum values of sperm quality.

Given that men suffering from oligospermia have a lower sperm count in the ejaculate than normal, it is more difficult that an egg could be fertilized with the sperm from these men, which may hinder pregnancy to occur naturally. This is the reason why oligospermia is considered to be a fertility problem.

Male infertility

Being this disease an alteration in the sperm levels, it is considered these men suffer from male infertility.

Among the population of reproductive age, it is thought between 12 and 18% of cases have fertility problems. In 20% the cause is joint: the man, as well as the woman, is affected, whilst in 30% of cases the cause has a male origin only. Overall, in 50% of situations, there are fertility problems in men.

There are different grades of oligospermia according to the number of sperm in the ejaculate:

  • Severe oligospermia
  • Moderate oligospermia
  • Mild oligospermia

There are numerical ranges that define a concrete type of oligospermia.

Although it causes male infertility, those men actually have sperm in their ejaculate, for this reason, through assisted reproductive techniques, they are able to fertilize the egg and achieve the pregnancy. Much more serious is the case in which there is no sperm found in the seminogram: this would be another sperm alteration, called azoospermia.

If you want to find out detailed information about oligospermia, we recommend you to follow the menu that you shall find on the left side of this page.


  1. Hi there! My husband underwent a seminogram and the result was that he had a low sperm count and his sperm is very slow, Besides, some present abnormal sperm morphology. He is a heavy smoker and I think that’s the cause behind these awful results… Can you tell me if tobacco has indeed an influence on sperm quality? Thanks.

    • Sandra F.
      ModeratorSandra F.

      Tobacco consumption affects all parameters of seminal quality, that is to say, morphology, concentration, and motility. Quitting smoking or at least reducing its consumption together with eating antioxidant-rich foods every day (fruit and vegetables) during at least 3 months in a row may boost his seminal quality.

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