Causes of male fertility

It was previously believed that infertility was mostly a female issue but it is now generally accepted that males are responsible for 40-50% of infertility cases.

If the male patient has no history of conceiving previous pregnancies, the infertility is called primary infertility.

If he has previously conceived a child or has children, but he is now struggling to conceive again, it is called secondary infertility. This is important to know because certain causes like congenital abnormalities can be excluded if the patient has previously conceived.

The causes of male infertility can be divided into four main categories:


Testicular pathology

The testicles are responsible for producing sperm. If any testicular pathology is present it could decrease the patient’s chances of conceiving by inadequate or abnormal sperm production. About 30-40% of causes of infertility in men are due to a testicular pathology.
The common testicular pathology causes of infertility are briefly discussed:

    Genetic reasons

    Genetic reasons

  • Genetic Reasons
  • 15-25% of Testicular pathology is as a result of genetic reasons.

    • Kleinfelter’s syndrome is an example of a genetic cause of infertility. This is a rare disorder where the person affected has XXY chromosomes present instead of XY (male) or XX (female). They have the physical features of a man because of the Y chromosome that is present but they have much less testosterone.
    • Cryptorchidism is when one or both testes are absent from the scrotum. It is common in the first year of life in male babies, especially in premature babies. The testes usually descend by 1 year of age. If the testis does not descend into the scrotum is it called cryptorchidism. Testes that are not in the scrotum cannot produce adequate sperm mainly because of increased temperatures. The undescended testis also has a big chance of developing cancer if it is not corrected while the child is young.
    • Cystic fibrosis is an autosomal recessive genetic disorder where 97% of patients with the disorder are infertile. It also affects the lungs, pancreas, liver an intestine.
  • Physical injury
  • Severe physical injury to the testes by trauma, heat, or radiation is a cause of infertility. Although the testes are in a vulnerable position, severe injuries causing infertility are quite rare. Testicular torsion which is caused by trauma must be treated quickly and early to prevent losing that testis. Men with one functioning testis are able to conceive.

  • Varicocele
  • A varicocele is a testicular reason for infertility. This is caused by an abnormal dilatation of the small veins in the scrotum. Not all varicoceles cause infertility.

  • Infection
  • Infections affecting the testes can result in infertility. The mumps virus can affect the testes and TB orchitis can also cause infertility when the testes are involved.

  • Cancer
  • There are several forms of cancer which can be a cause of male infertility. The treatments used in treating cancer can also cause infertility. The cancers which are most likely to cause infertility are survivors of testicular cancer, Hodgkin’s disease, leukemia and lymphoma. Chemotherapy, like Procarbazine, is cytotoxic which means it is poisonous to body cells. This does not only kill the cancer cells but also cells involved in sperm production.

  • Systemic/Metabolic disease (endocrine, malnutrition, renal failure, cirrhosis)
  • Many chronic illnesses and diseases are a cause of infertility. Diabetes, renal failure and cirrhosis are a few examples.

Sperm transport problems (Post-testicular pathology)

Sperm transport problems

Sperm transport problems

In 10-20% of male infertility cases the problem is the transport of sperm to the vagina. A blockage or defect occurs somewhere along the sperms’ pathway or there is an abnormality present which is preventing the delivery of sperm. A few common causes of sperm transport problems are discussed:

  • Abnormal position of urethral orifice
  • The urethral orifice is where the urethral opens to allow for urination and the ejaculation of sperm. Sometimes this opening is not at the tip of the penis but along the penile shaft which makes it difficult for the sperm to reach the cervix in the female vagina.

  • Erectile dysfunction
  • Erectile dysfunction has many different causes, but whatever the cause the result is usually infertility because the penis is unable to sustain an erection for long enough to allow adequate vaginal penetration.

  • Ejaculatory dysfunction
  • Patients can suffer from premature ejaculation which can result in ejaculation occurring before vaginal penetration. Retrograde ejaculation is when semen is redirected into the bladder instead of out of the urethral orifice. Retarded or delayed ejaculation is when a man is unable to reach orgasm even with sufficient sexual stimulation. In all of these cases the sperm cells do not reach the female cervix.

  • Obstruction of pathway of sperm
  • Any obstruction in the urethra or epididymus will hinder the flow and delivery of sperm. Recurrent urethral infections can cause urethral strictures and be an obstruction to sperm flow.

Hormonal problems

1-2% of the causes of male infertility are because of hormonal abnormalities. The following hormonal abnormalities are briefly discussed:

  • Abnormal testosterone production
  • Testosterone is needed for adequate production of sperm. There are many causes of decreased testosterone levels like chronic illnesses, some medications and life-style factors.

  • Thyroid abnormalities
  • Low thyroid hormone levels can interfere with the quality of sperm and also dramatically lowers libido.


Any reason that does not fit into any of the above categories or if no specific cause can be found, then the infertility is said to be unclassified or non-classified. This accounts for 40-50% of male infertility cases. If the cause is unclassified, it does not mean that the patient won’t benefit from treatment.