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Ovulatory disorders are a common cause
of infertility. Ovulation
is controlled by complex interactions between numerous
endocrine hormones including FSH, LH, estradiol, progesterone
and others. Imbalances in these hormones, or alterations
in the “feedback mechanism”, can prevent
ovulation, or cause it to be irregular. 
Clomid is often used to treat anovulation (lack
of ovulation) and if it does not work, injectable
drugs such as FSH
are employed. Injectable fertility drugs are often
combined with intrauterine
insemination (IUI).
In the ovary, FSH and LH provide a
signal for the development of eggs. As egg development
occurs, the hormones estrogen and inhibin, produced
by the ovary, provide negative feedback to the hypothalamus
and pituitary.
This feedback causes the production of FSH and LH
to decrease. In the failing
ovary, (pre-menopausal) estrogen and inhibin levels
are low; the negative feedback is inhibited; and FSH
and LH levels may be high, signifying imminent ovarian
failure.
The hypothalamus is an extremely sensitive part of
the human brain, especially in females. Changes in
diet, excessive weight gain or loss, stress, excessive
exercise, emotional upheaval, and even alterations
in the light/dark cycles may alter its function. These
alterations affect the GnRH pulses and hence pituitary
function with alteration in the secretion of the hormones
FSH and LH.
These changes affect ovarian function with alterations in the production of estrogen, which prepares the uterus to accept an embryo, and progesterone, the hormone of the luteal phase, which is important in maintaining a pregnancy. Thyroid hormone balance is also extremely important to the overall functioning of this system.
Because of the hormonal changes discussed above, a female undergoes a monthly menstrual cycle. In the first half of the cycle, (proliferative phase), the lining of the uterus is developed so that an embryo can implant. This is the estrogenic phase. The second half of the cycle is characterized by the secretion of progesterone (secretory phase) to maintain the lining of the uterus.
Ovulation is the event that occurs between the proliferative and secretory phases, and is usually mid cycle. At the end of the secretory phase (which usually lasts fourteen days), menstruation (shedding of the lining of the uterus) occurs if there is no pregnancy.
The hormonal events in a normal menstrual cycle are complex. FSH is secreted from the pituitary gland causing the ovaries to produce estrogen. Just before ovulation, the hormone LH is released from the pituitary gland, triggering an ovulatory response in the ovary. (This is a hormone measured in ovulation prediction kits and is in the blood stream for a short time).
Many conditions can cause irregular
ovulation including hyperprolactinemia.
This condition is caused by a tumor (usually benign)
located on the pituitary gland. Treatment with the
drug Parlodel is often very effective.
In most cases, ovulation is effectively established using fertility medications unless there is ovarian failure due to age or other causes.
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damaged
by pelvic inflammatory disease, previous surgery,