2. Causes of sub or infertility

The main reasons for which a couple may be relatively infertile (with a reduced monthly chance of conception - sub fertility) or completely infertile (with no chance of conception - infertility, sterility) are:

A) Female factor (40%)

• Problems with ovulation (the release of the egg from the ovary). Infertility will be the result of the complete absence of periods ("amenorrhoea"), although many of these patients will be treated with hormones or drugs. If there are no responsive follicles in the ovaries ("ovarian failure") the only possible treatment is egg or embryo donation.
  
  
• Any obstruction between the vagina and the ovary, preventing fertilization (the commonest site is the fallopian tubes - sometimes treatable with microsurgery, otherwise with assisted conception -IVF).
  
  
• Endometriosis, a common disease in which tissue like the lining of the uterus (the "endometrium") grows outside the uterus, hampering a number of events important to conception and implantation of the embryo treatment can be medical, surgical or with assisted conception. The disease causes usually sub fertility (and not complete infertility).

B) Male factor (40%)

• Problems with sperm quality, as reduced motility, reduced number of spermatozoa, and increased abnormal morphology. It is common not to find any reasons for these asthenoteratospermias.
  
  
• Problems with sperm production (often not treatable, except by assisted conception). There will be infertility if there are no spermatozoa in the ejaculate (azoospermia), even though problems due to obstruction of the tubes through which the spermatozoa travel to the penis can be treated.

C) Both couple factor (20%)

In these cases the problems are not individual for the female or male partner but rather the combination of both partners.