What is infertility?
The true definition of infertility is a total absence of any reproductive function. This is fairly rare and the term subfertility is more factually correct for most people who are having difficulty conceiving. However, in practice the term infertility is more commonly used and is usually taken to mean an inability to conceive after regular unprotected intercourse for 12 months or more. Many doctors will not start investigations until after this time. However, if there are risk factors, such as female age >35 years or a history of pelvic inflammatory disease (PID), earlier investigation may be warranted.
What causes infertility?
There are many pre-existing conditions that may lead a woman to suspect that she may be infertile without the need to try to conceive for 12 months or more, including:
- Past or current PID, which can lead to blockage of the fallopian tubes (PID can result if chlamydia infection is left untreated)
- Endometriosis–a condition in which the cells that make up the lining of the uterus (womb) also grow outside the uterus, causing severe pain and in some cases leading to blockage of the fallopian tubes
- Large fibroids in the uterus, which may prevent the implantation of a fertilized egg
- Severe weight problems such as obesity, which can alter the normal hormonal balance of the body
- Anorexia, which can lead to the absence of periods
- Polycystic ovaries
- Hormonal imbalance
Fertility also declines with age. At 35 a woman is half as fertile as a woman of 21 and by 40 she has a one in three chance of being infertile. An early menopause will cause fertility to be lost at an earlier age than normal.
Age can also be relevant to male fertility but men usually remain fertile for most of their lives. Undescended testes can cause fertility problems as can any previous radiation treatment for cancer. Other causes of male infertility include insufficient hormone levels, which may affect sperm production, and structural problems in the route through which sperm travels, which may be caused by infection, injury, hernia or prostate surgery. In some cases the mucus in a woman’s vagina may be hostile to her partner’s sperm and prevent it from entering the cervix. In some cases the cause of infertility may not be identifiable.