Reasons for infertility: Male factors

Male sterility is best diagnosed by an analysis of his ejaculated sperm. In our andrology lab sperm concentration, morphology and motility are analyzed after strict WHO-criteria. Besides physical factors sterility in men can be influenced by external factors as nicotine, alcohol, medication, stress, infections, pollutants and malnutrition.

Hormonal factors

Hormonal factors can also influence the quality of human semen. The pituitary gland produces two hormones important for the development of sperm: FSH and LH. They are responsible for the secretion of testosterone and for the formation of sperm.


If varicoceles are present, the tissue is too much perfused an the temperature in the testicular tissue increased,which impaires spermatogenesis.

Undescended testis

In most boys, his testicles typically form inside his abdomen and move down into the scrotum shortly before birth. But in some cases, that move or descent doesn’t occur, and the baby is born with a undescended testicle. This should be treated before his 2nd birthday. Otherwise the testis is exposed to higher than normal temperatures and this can lead to an irreversible reduction in sperm quality.


If a boy or a young man is infected by the mumps virus, in 30% the virus infects the testicles. It starts during the first week of infection with fever and painful swelling of usually one testis. In 13% of the cases sperm quality is impaired. In some rare cases even infertility occurs.


In a few cases a reduction in sperm quality can be an indication for testicular cancer. Men with infertility have a higher risk to get testicular cancer, especially after having suffered from undescended testis as a child. If sperm quality is severely impaired, we recommend an appointment with an urologist, who will perform an ultrasound guided checkup of the scrotum.

Erectile dysfunction

Erectile dysfunction can have many causes. Physical origins like diseases of the nervous system (spinal cord injuries, multiple sclerosis), mental reasons (problems within the partnership, stress, depression) or even can be caused by side effects of certain medication.


Diabetes can cause a narrowing of blood vessels. The penis thus is less supplied with blood. The patients often additionally suffer from high blood pressure. The nervous system also can be damaged by an increased blood glucose level. Then erectile dysfunction can be the result.


Sterilisation in principle is reversible. But sperm quality after refertilisation often is decreased, dependend on the length of sterilization. The longer the time period, the less sperm is produced in the testis. Alternatively, sperm can be then retrieved by testicular sperm extraction (TESE) directly from the testis. With these spermatozoa ICSI can be performed.

Age as a factor

The number of motile sperm decreases with age.


Smokers sometimes have slower sperm. To stop smoking increases sperm quality.


The intake of hormones to stimulate muscular growth (anabolics, testosterone) can lead to azoospermia (no spermatozoa present in the ejaculate). If the intake of these substances is stopped, sperm production is resumed.