There are many possible causes of infertility but in 20% of cases, no cause is ever found.

Female factors generally account for 40% of cases of infertility.

Male factors account for the other 40%.

Medical conditions

Medical conditions like thyroid disease and diabetes may affect your fertility. It may be dangerous to become pregnant if you do not have these conditions under good control.

Treatments such as chemotherapy could affect your fertility whether you are a woman or a man.

Having mumps in the past may affect male fertility.


Certain medications affect your fertility and may be unsafe to take during pregnancy.

Tell your GP if you are taking any over-the-counter medications or herbal remedies.


Certain types of contraception may take some time to stop working. Some women may become pregnant quickly. For other women it can take up to a year for fertility to return to normal.

Problems with sex

Problems with sex can delay couples from becoming pregnant and may be easy to treat. Your GP is used to talking to couples about sex and will be non-judgmental.

Trying to become pregnant can be stressful. This can lead to problems with sex. Or you may have had problems with sex before you began trying to get pregnant.

Problems with sex could include:

  • The man having difficulty getting an erection (sometimes called impotence).
  • Reduction in libido (loss of interest in sex).
  • The man having difficulty achieving orgasm.
  • Pain on having sex (more common in women than men).

Page last reviewed: 10 May 2019
Next review due: 10 May 2022