Ovarian reserve is an important factor in female fertility. Testing for diminished ovarian reserve gives couples the advantage of a realistic estimate of the likelihood of fertility without treatment. Measurement can only be approximated; there is no precise test available.
Causes of Diminished Ovarian Reserve
Ovarian reserve may be thought of as a health check of the ovaries and the eggs they contain. There are several reasons that ovarian reserve may be diminished:
- Surgeries on the ovary or ovaries
- Removed ovary
Diminished ovarian reserve is also common in many patients with unexplained infertility. Women with diminished ovarian reserve may be counseled to consider using donated eggs or adoption.
Women whose fertility is declining due to age have an additional obstacle to pregnancy – increased miscarriage risk. Expected miscarriage rates correspond with age:
- 7 percent to 15 percent for women under age 30
- 9 percent to 21 percent for ages 30-34
- 17 percent to 28 percent for ages 35-39
- 35 percent to 52 percent for women over age 40
Measuring Ovarian Reserve
Ovarian reserve is estimated by measuring follicle stimulating hormone (FSH) levels. A high FSH value indicates that one or both ovaries are not working well.
A woman’s brain monitors the hormones her ovary produces and, if it judges these to be deficient, the brain attempts to stimulate the ovary to produce more by sending a higher signal – resulting in a higher FSH level.
Ovarian reserve is frequently calculated by measuring the level of FSH on cycle day three (day one is the first day of menstruation) along with an estrogen level.
In some cases, a more provocative test is used. In the clomiphene citrate challenge test (CCCT), day three FSH levels are recorded. The woman then takes the fertility medication clomiphene citrate for cycle days five through nine. The FSH measurement is then repeated on cycle day 10. Clomiphene blocks hormone receptors in the brain, causing an increase in FSH. The elevated FSH triggers the ovary to make more hormones, which should cause FSH levels to subside. An elevated level on day three or 10—or both days—indicates diminished ovarian reserve.
Understanding Ovarian Reserve Test Results
Some important concepts must be kept in mind when considering testing:
- High FSH levels predict low fertility, but they do not accurately predict high fertility when normal.
- The specific FSH assay system used in a laboratory affects the level used to indicate diminished ovarian reserve.
- Diminished ovarian reserve does not mean a woman cannot become pregnant —only that she is less likely to be successful if she uses her own eggs.
- There is no need to repeat an abnormal test; the available evidence suggests that fertility estimates are more reliably based on the worst FSH value, not the best.
Some programs will not allow a woman with diminished ovarian reserve to undergo IVF treatment with her own eggs. Sometimes this may be done to protect a clinic’s success rates. The Reproductive Medicine Center takes an individual approach to these patients. If, after counseling about poor prognosis, a patient wants to proceed, we generally allow her to go through a cycle.