Causes of Female Infertility
The most common causes for female infertility is ovulatory disorders. Without ovulation, fertilization and pregnancy cannot occur. Ovulatory disorders are characterized by anovulation (complete failure to ovulate) or infrequent and/or irregular ovulation. These account for approximately 20-30% of female infertility.
Ovulatory disorders are often the result of hormone imbalances. Polycystic ovarian disease (PCOD, a condition commonly characterized by hirsutism, obesity, menstrual abnormalities, infertility and enlarged ovaries; thought to reflect excessive androgen secretion of ovarian origin) or a malfunction of hypothalamus, pituitary or adrenal gland are often responsible. Reasons for anovulation also include damage of the ovaries themselves (previous surgery resulting in scar tissue formation for example), premature menopause with follicle problems ( the follicle fails to rupture andrelease the egg) and hyperprolactinaemia ( condition of increased levels of prolactin hormone in the blood). Hyperprolactinaemia is associated with infertility as it has an inhibitory effect on cyclical ovarian function, probably due to direct inhibition of GnRH secretion.
The WHO has adopted a treatment -oriented classification of anovulating patients:
- Group I patients have hypothalamic-pituitary failure. They are amenorrheic and lack both FSH and LH.
- Group II patients have hypothalamic-pituitary dysfunction and present with a variety of cycle disorders including amenorrhoea, oligomenorrhoea, and luteal phase deficiencies.. About 97% of anovulatory patients fall into this group, including PCOD, which is thought to be the most common cause of ovarian dysfunction.
Fallopian Tube Damage
Damage to the fallopian tubes is another common cause for female infertility, occluding or partially obstructing the tube and thus preventing the egg from traveling down to be fertilized by the sperm. Tubal damage can result from salpingitis (inflammation of the tubes) caused by becterial and viral infection, sometimes but not always, caused by sexually transmitted diseases. Surgery itself can create abdominal adhesions and scar tissue that can also damage the fallopian tubes.
Uterine and cervical disorders
Abnormalities of the uterus such as fibroids, and polyps (acting like intrauterine contraceptive devices - IUCD) can contribute to infertility by causing damage to the uterine wall. Likewise, abnormalities of the cervix or the cervical mucus can reduce fertility. Mechanical problems accounts for between 20% to 30% of female infertility.
Endometriosis, although reasonably uncommon, is associated with a high incidence of infertility (approximately 70% of sufferers experience infertility). Endometriosis is a condition whereby endometrial tissue grows outside the uterus. Endometrial lesions can cause blocked fallopian tubes and/or impaired ovulatory function.
Immunological factors such as antibodies to the man's sperm within cervical mucus can cause infertility. There is much that is still not understood within this area making the treatment difficult.
Endometriosis, hyperprolactinaemia and 'other' causes account for approximately 10-20% of female infertility.