Medical Causes

Testicular diseases

Diseases of testis and epididymis, such as inflammation, varicocele or testicular torsion affect mostly younger men and are very serious, as they may affect fertility with delayed treatment.

Hormonal dysfunction

Hormones, in particular the hormone FSH, control the production of sperm in the testicles. Hormone treatment is recommended with insufficient production or effect of FSH.

Varicose veins in the testicles (varicocele)

Varicocele are varicose veins in the testicles and the spermatic cord. Approx. 15% of all men are affected by this. Untreated varicocele frequently cause male infertility as the build-up of blood in the scrotum leads to an increase in temperature in the testes by 0.5-1° C, which in turn has an adverse effect on sperm production. In 25-40% of infertile men varicocele are the cause of infertility.

Antibodies to sperm

As sperm are not produced until the age of puberty, the body may recognise them as foreign and thus produces antibodies to sperm. These antibodies can reduce the chances of getting pregnant.

Disorder of vas deferens

The final maturation of sperm occurs in the epididymis. The epididymis is a duct system of two to four metres length, through which the sperm is transported. Even minor infections can lead to blockage. Due to this disruption of sperm transport, sperm cannot mix with seminal fluid; there are not enough or abnormal sperm in the ejaculate.

Lifestyle Causes

Where no medical reason is diagnosed for infertility, modern science assumes that infertility is primarily caused by diet and lifestyle.

Being overweight or obese

Being 10kg overweight increases the risk of infertility by 10%. Particularly the increase in abdominal fat leads to a reduction of free, biologically active rate of testosterone.


Smoking affects sperm density, sperm motility (movement) and sperm morphology (appearance). A direct effect on testicular function and spermatogenesis is suspected. Metabolites of cigarette smoke components may induce an inflammatory reaction in the male genital tract, which in turn can result in oxidative damage to the sperm due to reactive oxygen radicals.


Severe chronic alcohol abuse can be directly toxic to the testes. It manifests itself in spermatogenesis arrest including Sertoli cell-only syndrome as well as abnormal sperm motility and morphology


Dietary deficiencies can lead to the development of nutritional deficiencies and subsequently to reduced sperm quality. Vitamins and micronutrients, in particular, which the body must get from food, serve as a cofactor for the enzyme reactions and have an antioxidant effect.