| 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.
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.
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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.
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