Ovarian reserve is a term fertility doctors use to describe a woman’s reproductive potential with respect to egg quantity. This evaluation can be helpful in determining how aggressive a woman should be with infertility treatment and importance of time.
We have a few practical ways to evaluate ovarian reserve including blood testing for FSH and AMH, and antral follicle count determined by ultrasound.
A blood FSH (Follicle Stimulating Hormone) level taken on the second or third day of a menstrual period, is a helpful test, and has been the traditional measurement of ovarian reserve. General guidelines are that an FSH level less than 10 is reassuring; 10-14 is borderline, suggesting that time is important; and a level above 14 predicts low success with most fertility treatments. A woman’s FSH level varies from cycle to cycle and generally speaking, the ovaries will act like the worst ever FSH level recorded. So a bad FSH level tends to be fairly predictive, but a good FSH level is less predictive of a good response or good number of eggs developing with fertility treatment, because the FSH level could have been higher in previous months. Even a high FSH level is however somewhat age related, so an abnormal FSH in a 30 year old is not as predictive of low pregnancy rate as an abnormal FSH in a 40 year old. Also some patients with very high FSH levels may even get pregnant without any treatment.
A newer blood test to evaluate ovarian reserve is AMH (Anti Mullerian Hormone). AMH blood levels correlate with the granulosa cell production from the small developing follicles in the ovary. In general the more follicles (egg sacs) you have, the higher the AMH level. AMH levels have been shown to correlate well with the number of eggs retrieved in IVF cycles. AMH is NOT influenced by the day of the menstrual cycle so blood can be taken at any time for this test (even if a woman is on birth control pills or breast feeding). It also appears to fluctuate much less than FSH month to month. A very high AMH level correlates with a tendency to over respond to fertility medication, suggesting the need for a lower dose of medication.
In general an AMH above 2.0 corresponds with good ovarian reserve, less than 1.0 is concerning for depletion of eggs, and less than 0.1 a very low chance for pregnancy with fertility treatment. A level above 3.5 corresponds with an increased risk for overstimulation of the ovaries.
Another way of assessing ovarian reserve is a pelvic ultrasound to look at antral follicle count. Antral follicles are small (3-6 mm) follicles seen at any time on a woman’s ovaries. In general the more antral follicles the stronger the response to fertility medication and the higher the number of eggs retrieved in an IVF cycle.
An antral follicle count below 5 is considered very low, 10- 15 is fairly average, and above 20 indicates a strong response to fertility medication.
FSH, AMH, and Antral Follicle Count are all tools infertility physicians use to evaluate ovarian reserve. They help to guide you on how aggressive to be with fertility treatment, and guide us in the appropriate dose of fertility medication. These tests are helpful in predicting egg quantity, but there are no good tests to predict egg quality. In general a woman’s age is the best predictor of egg quality.