The main causes of female infertility are:
Women with ovulation disorders may ovulate infrequently or not at all. This accounts for around a quarter of female infertility. Polycystic ovarian syndrome (PCOS) is one of the most common causes affecting ovulation, Other causes include ovarian insufficiency and hypothalamic amenorrhoea. Lifestyle factors may also affect ovarian function such as smoking, alcohol consumption and the use of recreational drugs. Excessive weight loss or gain may also affect ovulation.
Blockage of the Fallopian tubes
The Fallopian tubes can become damaged or blocked for a number of reasons such as a history of pelvic infection, a previous burst appendix, sexually transmitted diseases (such as gonorrhoea and chlamydia), endometriosis, and previous abdominal surgery.
Endometriosis occurs when cells of the uterine lining (endometrium) flow backwards out of the Fallopian tubes and grow outside the uterus in various locations in the abdomen and or pelvis, commonly on the ovaries. These deposits are affected by the hormonal changes during the menstrual cycle, growing during the cycle and ‘bleeding’ when the period starts. As this blood has no exit route, these accumulations month after month can lead to scar formation and adhesions. Endometriosis is a common condition affecting around 5-10% of women of reproductive age and up to one third of women with infertility.
Uterine fibroids are benign growths in the uterus and are very common (approximately 40% of women have them). The effect on fertility will depend on the location of the fibroid. Fibroids that distort the uterine cavity can affect the ability of the embryo to implant and may need removing.
Endometrial polyps, which are growths in the uterine cavity, may also interfere with the implantation process and should be removed.
An abnormally shaped uterus may also prevent pregnancy or cause miscarriage.
Infertility due to the advanced age of the woman is one of the commonest causes of female infertility. As a woman becomes older, the number and quality of her eggs decrease rapidly, therefore, reducing the chance of pregnancy. The chance of miscarriage also increases due to the higher incidence of chromosomal abnormalities within the eggs of older women.
Disorders of the immune system, autoimmune disorders and recurrent miscarriage
Reproductive immunology of pregnancy refers to a field of medicine that studies maternal tolerance towards the foetus. Observed changes in the immune profile of women with reproductive failure have been suggested as a possible reason for infertility, recurrent failed implantation, recurrent miscarriage and pre-eclampsia.
This diagnosis accounts for approximately 25% of couples seeking fertility treatment. Additional specialist investigations may be required prior to further treatment.