Other possible causes

Average rating:

Fallopian tube, cervix or uterine problems

These are the cause in about 2 in 10 couples with infertility, and include the following:

Endometriosis causes about 1 in 20 cases of infertility. See separate leaflet called 'Endometriosis' for more detail. Very briefly, tissue that lines the uterus (endometrium) is found outside of the uterus. It is 'trapped' in the pelvic area and can affect the ovaries, uterus, and nearby structures. It often causes lower abdominal pain and/or painful periods.
Previous infection of the uterus and fallopian tubes (pelvic inflammatory disease) is another common cause. Chlamydia infection can be a cause of pelvic inflammatory disease (PID). PID can cause scarring and damage which can affect fertility. For example, scar tissue may block the egg (ovum) from travelling down the fallopian tubes. See separate leaflet called 'Pelvic Inflammatory Disease' for more detail.
Previous surgery to the fallopian tubes, cervix or uterus can cause scarring.
Large fibroids may also cause problems, although this is debated by some experts. A fibroid is a benign (non-cancerous) growth of the uterus (womb). See separate leaflet called 'Fibroids' for more detail.

Male problems

These occur in about 2 in 10 cases. Some men are born with testes that do not make any sperm, or very few sperm. Some are born without testes or without a vas deferens.

The most common reason for male infertility is a problem with sperm due to an unknown cause. The sperm may be reduced in number, less mobile (less able to swim), and/or be abnormal in their form.

There are a variety of things that may affect sperm production and male infertility. These include:

Certain hormone problems.
Current or past infection of the testes.
Tumours of the testes.
Testes that haven't descended (dropped) properly.
Side-effects of some medicines and street drugs. These include: sulfasalazine, nitrofurantoin, tetracyclines, cimetidine, colchicine, allopurinol, some chemotherapy drugs, cannabis, cocaine and anabolic steroids.
Smoking may also be a factor.
Being overweight can affect male fertility.
Regular excess heat (regular saunas, hot baths, etc) is possibly a cause.
Environmental factors may be relevant in some men. For example, a lot of exposure * A varicocele may possibly affect male fertility. A varicocele is common and is like a 'varicose vein' in the scrotum (the skin that covers the testes). Varicoceles are found in just over 1 in 10 men with normal sperm and 1 in 4 men with abnormal sperm. See separate leaflet called 'Varicocele' for more detail.

Unknown

No cause can be found in about 3 in 10 cases of infertility.

Age is a factor

Older women tend to be less fertile than younger women. The 'fall off' of fertility seems to be greatest once you are past your middle 30's. For women aged 35-39 the chance of conceiving is about half that of women aged 19-26.