Causes of infertility

Female infertility

Dysfunction with egg maturation

Hormone production and distribution are influenced by various factors. Stress, certain medications, weight or thyroid disorders could have a negative impact on hormonal balance. An imbalance in the body’s hormone levels has a significant influence on the natural process of a woman’s menstrual cycle. For example, egg maturation and subsequent ovulation may be inhibited or not take place at all.

Infertility due to the fallopian tubes

After ovulation, the egg lands in the fallopian tube. In the fallopian tube, the sperm then have the opportunity to fertilise the egg. In approximately one-third of women, the fallopian tubes are damaged or obstructed, which causes involuntary childlessness. The delicate fallopian tubes can be damaged for several reasons, such as inflammation, previous ectopic pregnancies or adhesions after an operation. Endometriosis – spontaneous proliferation of the lining of the uterus outside of the uterus – can also clog the fallopian tubes and prevent the sperm from reaching the egg.

Myomas

Benign growths in the uterine muscle can grow inside the uterus, in the uterine wall or outside the uterus. Depending on the position and size, these harmless tumours can have an influence on fertility. Inside the uterus, these occupy the area where a fertilised egg should implant on the endometrium. Should the myoma (or fibroid) press against the fallopian tubes or the cervix, fusion of the egg and sperm becomes more difficult. In addition, typical symptoms of myomas, such as intermenstrual bleeding and inflammation, have a negative influence on fertilisation and embryo implantation.

Abnormalities in the reproductive organs

The reproductive organs must be intact so that a sperm can fertilise the egg. In about 5% of women, abnormalities in the ovaries, fallopian tubes or uterus are the cause of infertility. The abnormalities are usually hereditary and occur in different forms.

Antibodies against sperm

If the man’s sperm enter the woman’s body, they are sometimes initially perceived as undesirable foreign objects. Antibodies in the cervical mucus of the uterus then start fighting the sperm and slow them down. This process, which prevents fertilisation of the egg, is called an immunological problem.

Examination methods at a glance

• Ultrasound examination to look at the reproductive organs

• Blood sampling to determine hormone values

• Basal temperature curve to define the time of ovulation

• X-ray examination with contrast medium to detect blockages in the fallopian tube

• Laparoscopy (abdominal examination) to carefully examine the abdominal area and remove small obstructions

Male infertility

Dysfunctional sperm maturation

The most common problem with fertility in men is the insufficient production of normal, motile sperm in the testes. Semen quality is considered normal when the number of sperm cells is over 20 million per millilitre of semen. Of these, at least 15 percent should be normally formed and 25 percent should have good forward mobility. If these values are not achieved, the man’s fertility is reduced. However, even if the sperm count is normal, a functional problem could still prevent the sperm from penetrating the egg.

Dysfunction in sperm maturation can result from a mumps infection in childhood. Varicose veins on the testes (varicocele) can also cause poor sperm motility.

Other causes are hormonal problems, stress, environmental pollution, undescended testicles, tumours that have been operated on or genetic causes, such as chromosomal abnormality. Acute infections can also temporarily reduce sperm motility.

Dysfunctional sperm transport

In four percent of cases, sufficient sperm is actually formed – but these fail to penetrate the woman’s body during ejaculation because the seminal ducts are blocked.

This situation is comparable to a blocked fallopian tube in the woman. It could be caused by prior sterilisation, undeveloped epididymis or adhesions in the epididymis. Adhesions in the epididymis may result from infections.