Anovulation is a condition in which the ovary does not release a ripened egg each month as part of a woman's normal cycle in her reproductive years. Naturally, with no egg available for sperm, a woman cannot become pregnant. Thus, anovulation is a prime factor in infertility.
While anovulation and its role in infertility seems simple, the condition itself is quite complicated. Anovulation can arise from a number of causes, ranging from diet and exercise to complex disruptions in the relationships between tiny glands in the brain that control our most basic functions.
Anovulation can also be difficult to detect. Some women have seemingly normal menstrual periods even though they are not ovulating. Most often, women who do not ovulate also do not menstruate, a disorder known as amenorrhea, or do not menstruate regularly, a condition called oligomenorrhea. Because of this tendency, scant, erratic, short and/or painless menstrual cycles can sometimes alert a woman or her doctor to an anovulation problem. Physicians are now increasingly skilled at using modern diagnostic techniques and assisted reproductive technologies.
It is important to consider individual differences among women. Some, for example, have extremely sound and well-structured endocrine feedback mechanisms, and ovulate like clockwork each month no matter what happens. Others have endocrine systems that are much more sensitive to interruption. Moreover, anovulation can also be caused by underlying diseases that seem completely unrelated to reproduction.
Some causes are relatively easy to identify, whereas others are much more difficult. A number of possible causes can be identified:
Excessive exercise and weight loss. A prolonged, strenuous program of exercise, such as running, can interfere with the ovulatory cycle by suppressing the output of hormones called gonadotropins from the hypothalamus in the brain.
This type of anovulation is generally accompanied by amenorrhea and normal menstruation returns when the woman adjusts her regimen so that it is more in since with her body's physiology.
Stress.Anxiety and other forms of emotional stress can take a their toll on normal ovulation. Some women can resolve the stress in their daily lives while others need the help of a psychiatrist or psychotherapist. Occasionally, through therapy or meditation, a woman will gain insight into a subconscious but significant reservation she has about becoming pregnant.
Drugs. Another possible contributor to anovulation is the long-term use of certain medications. Steroidal oral contraceptives (the Pill) are sometimes responsible. These drugs work by intentionally disrupting the hypothalamic-pituitary-ovarian axis, suppressing ovulation and thereby preventing pregnancy. For women using long-acting injectable steroid contraceptives (Depo-Provera), it appears likely that the longer the contraceptive is continued the more likely it is that amenorrhea will result.
Other causes. These might include estrogen and progesterone imbalances. a malfunctioning corpulsteum, congenital adrenal hyperplasia, premature ovarian failure, and hyperprolactinemia.
The diagnosis of anovulation may require blood tests to measure the levels of prolactin, thyroid-stimulating hormone, adrenal function (DHEA), and male and female sex hormones (LH, FSH, and testosterone). It may necessitate use of ultrasound, MRI, CAT scan, and even laparoscopy.
Most fertility drugs are, in fact, medications to induce ovulation. For many infertile women with anovulation, treatment with one or another of these drugs can be remarkably successful. Clomiphene citrate (Clomid) is often a good first choice for an anovulatory woman who is producing estrogen.
Clomiphene induces ovulation by stimulating the pituitary to release gonadotropins, namely FSH, in much the same manner that GnRH does. Some studies have shown that 42 percent to 57 percent of patients ovulated after receiving clomiphene, and 31 percent of them became pregnant.
If clomiphene alone is unsuccessful, Pergonal is added to bolster the attempts to ripen a follicle. Pergonal bypasses the natural hormone stimulation of the pituitary on the ovary. It applies stimulation directly to the ovary, and then, once a follicle grows to sufficient size, HCG is used as the final step to release the egg.