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Causes of Infertility

Difficulty getting pregnant can be caused by lots of different things.

In women, infertility is most commonly caused by problems with ovulation (the monthly release of an egg). Some of these problems stop women releasing eggs at all, and some cause an egg to be released in some months and not others. This can happen as a result of:

  • Early menopause;
  • Polycystic ovarian syndrome;
  • Hormone problems (making too much or too little of certain hormones);
  • Being very underweight or overweight (ovulation often stops in women with anorexia);
  • Exercising too much;
  • Sexually transmitted infections (STIs), such as chlamydia and gonorrhoea;
  • Side-effects of some medicines, such as anti-inflammatory painkillers, chemotherapy and radiation treatment (often used to treat cancer);
  • Ovarian cysts;
  • Certain genetic problems; and
  • Certain chemicals in the environment.

Fertility problems in women can also be caused by conditions affecting the Fallopian tubes or urinary system, including:

  • Endometriosis (a condition in which womb lining appears in other parts of the body, including the reproductive organs);
  • Infection of the uterus (womb) and Fallopian tubes (pelvic inflammatory disease);
  • Surgery to the Fallopian tubes or uterus (womb); and
  • Large fibroids or cysts.

Infertility in women is also linked to age. Women in their early twenties are about twice as fertile (likely to get pregnant) as women in their late thirties. The biggest decrease in fertility appears to happen around the mid thirties.

In men, infertility is usually caused by a problem with the sperm. Some men don’t make any sperm, very few sperm or poor quality sperm. This can be caused by:

  • Hormone problems;
  • Infections of the testicles;
  • Tumours of the testes (testicles);
  • Side-effects of some medicines, including chemotherapy, radiation and illegal drugs;
  • Spending a lot of time in hot environments – ie – saunas and hot baths;
  • Environmental factors – ie - a lot of exposure to chemicals, X-rays, or heavy metals ; and
  • Varicocele (similar to a 'varicose vein' in the scrotum). Sometimes doctors can’t find a cause for infertility. This happens in three out of ten cases.