Anovulation And Ovulatory Dysfunction
Anovulation means lack of ovulation, or absent ovulation. Ovulation is the release of an egg from the ovary. This must happen in order to achieve pregnancy naturally. If ovulation is irregular, but not completely absent, this is called oligo-ovulation.
Both anovulation and oligo-ovulation are kinds of ovulatory dysfunction. Ovulatory dysfunction is a common cause of female infertility, occurring in up to 40 percent of infertile women.
Anovulation and Infertility
For a couple without infertility, the chances of conception are about 25 percent each month. Even when ovulation happens normally, a couple isn't guaranteed to conceive. When a woman is anovulatory, she can't get pregnant because there is no egg to be fertilized. If a woman has irregular ovulation, she has fewer chances to conceive, since she ovulates less frequently.
Plus, late ovulation doesn't produce the best quality eggs. This may also make fertilization less likely. Also, irregular ovulation means the hormones in the woman's body aren't quite right.
These hormonal irregularities can sometimes lead to other issues, including:
- Lack of fertile cervical mucus
- Thinner or over-thickening of the endometrium (where the fertilized egg needs to implant)
- Abnormally low levels of progesterone
- A shorter luteal phase
Usually, women with anovulation will have irregular periods. In the worst case, they may not get their cycles at all. If your cycles are shorter than 21 days, or longer than 36 days, you may have ovulatory dysfunction. If your cycles fall within the normal range of 21 to 36 days, but the length of your cycles varies widely from month to month, that may also be a sign of ovulatory dysfunction.
For example, if one month your period is 22 days, the next it's 35, that many variations between cycles could signal an ovulation problem. It is possible to get your cycles on an almost normal schedule and not ovulate, though this isn't common. A menstrual cycle where ovulation doesn't occur is called an anovulatory cycle.
Anovulation and ovulatory dysfunction can be caused by a number of factors. The most common cause of ovulatory dysfunction is polycystic ovarian syndrome (PCOS). Other potential causes of irregular or absent ovulation include:
- Too low body weight
- Extreme exercise
- Premature ovarian failure
- Perimenopause, or low ovarian reserves
- Thyroid dysfunction (hyperthyroidism)
- Extremely high levels of stress
Your doctor will ask you about your menstrual cycles. If you report irregular or absent cycles, ovulatory dysfunction will be suspected. Your doctor might also ask you to track your basal body temperature at home for a few months.
Next, your doctor will order blood work to check hormone levels. One of those tests might include a day 21 progesterone blood test. After ovulation, progesterone levels rise. If your progesterone levels do not rise, you are probably not ovulating. Your doctor may also order an ultrasound. The ultrasound will check out the shape and size of the uterus and ovaries, and also look to see if your ovaries are polycystic, which is a symptom of PCOS.
Ultrasound can also be used to track follicle development and ovulation, though this isn't commonly done. In this case, you might have several ultrasounds over a one- to two-week period.
Treatment will depend on the cause of the anovulation. Some cases of anovulation can be treated by lifestyle change or diet. If low body weight or extreme exercise is the cause of anovulation, gaining weight or lessening your exercise routine may be enough to restart ovulation. The same goes for obesity. If you are overweight, losing even 10 percent of your current weight may be enough to restart ovulation.
The most common treatment for anovulation is fertility drugs. Usually, Clomid is the first fertility drug tried. If Clomid doesn't work, there are other fertility treatments left to try.
Clomid can trigger ovulation in 80 percent of anovulatory women, and help about 45 percent get pregnant within six months of treatment.
For women with PCOS, insulin-sensitizing drugs like metformin may help a woman start ovulating again. Six months of treatment is required before you'll know if the metformin will work. Afterward, try taking a pregnancy test. If metformin alone doesn't help, using fertility drugs in combination has been shown to increase the chance of success in women who didn't ovulate on fertility drugs alone. The cancer drug letrozole (Femara) may be more successful at triggering ovulation in women with PCOS.
If the cause of anovulation is premature ovarian failure or low ovarian reserves, then fertility drugs are less likely to work. But that doesn't mean you can't get pregnant with your own eggs. Some women will be unable to conceive with their own eggs and may require IVF treatment with an egg donor.