Male infertility is caused by abnormal semen (the fluid containing sperm that is ejaculated during sex). Some possible reasons for abnormal semen are listed below.

  • Decreased number of sperm – You may have a very low sperm count, or no sperm at all.
  • Decreased sperm motility – If you have decreased sperm motility, it will be harder for your sperm to swim to the egg.
  • Abnormal sperm – Sometimes sperm can be an abnormal shape, making it harder for them to move and fertilise an egg.
  • Many cases of abnormal semen are unexplained, but there are several factors that can affect semen and sperm.

1. Testicles

The testicles are responsible for producing and storing sperm. If they are damaged it can seriously affect the quality of your semen. This may occur if you have, or have had in the past, any of the following:

  • An Infection of your Testicles
  • Testicular Cancer
  • Testicular Surgery
  • A Congenital Defect (a problem with your testicles that you were born with)
  • Undescended Testicles (when one or both of your testicles has not descended into the scrotum)
  • Trauma (injury) to your Testicles

2. Absence of sperm

Your testicles may produce sperm, but it may not reach your semen. The absence of sperm in your semen is known as obstructive azoospermia. This could be due to a blockage in one of the tiny tubes that make up your reproductive system, which may have been caused by an infection or surgery.

3. Sterilisation

A vasectomy is the surgical procedure for male sterilisation. It involves cutting and sealing off the vas deferens (the tubes that carry sperm out of your testicles), so that your semen will no longer contain any sperm. A vasectomy can be reversed, but reversals are not usually successful.

4. Ejaculation disorders

Some men experience ejaculation problems that can make it difficult for them to ejaculate. Other ejaculation problems include:

  • Retrograde Ejaculation, where semen is ejaculated into your bladder
  • Premature Ejaculation, where ejaculation occurs too quickly

5. Hypogonadism

Hypogonadism is an abnormally low level of testosterone, the male sex hormone that is involved in making sperm. This could be due to a tumour, taking illegal drugs or Kallman's syndrome (a rare disorder caused by a faulty gene) etc.

6. Medicines and drugs

Certain types of medicines can sometimes cause infertility problems. These medicines are listed below.

Sulfasalazine, an anti-inflammatory medicine used to treat conditions such as Crohn's disease (inflammation of the intestine) and rheumatoid arthritis (painful swelling of the joints). Sulfasalazine can decrease the number of sperm, but its effects are temporary and your sperm count should return to normal when you stop taking it.

Anabolic steroids, often used illegally to build muscle and improve athletic performance. Long-term use or abuse of anabolic steroids can reduce sperm count and sperm mobility.

Chemotherapy – Medicines used in chemotherapy can sometimes severely reduce sperm production.

Herbal remedies – Some herbal remedies, such as root extracts of Tripterygium wilfordii (a Chinese herb), can affect the production of sperm or reduce the size of your testicles.

7. Alcohol

Drinking too much alcohol can damage the quality of your sperm. Drinking more could make it difficult to conceive.