Ovarian reserve is a term used to refer to the number of eggs a woman has in her ovaries. Women are born with all the eggs the body produces for life, and as they age, the number of eggs declines. Women in their late teens and 20s tend to have numerous eggs, while women in their late 30s and 40s have very few. The number of eggs available has a direct impact on fertility and thus ovarian reserve is important for people trying to get pregnant, as well as those pursuing infertility treatment after unsuccessful attempts to get pregnant independently.
It is not possible to literally measure the number of eggs a woman has left in her ovaries. However, there are tests that can provide some clues. Hormonal blood tests to check on levels of Follicle-Stimulating Hormone (FSH) and Anti-Mullerian Hormone (AMH) can indicate how hard the body has to work to provide fertile eggs in each menstrual cycle. Low levels indicate relatively large numbers of eggs and minimal effort on the part of the body to encourage an egg to mature and become fertile.
Another option is a challenge test. Challenge tests to measure ovarian reserve are usually used during infertility treatment. The patient's FSH is measured and then she is given hormones and tested again after several days to see what happens when the ovaries are stimulated with the hormones. Ovarian reserve can also be estimated with the assistance of diagnostic ultrasound to examine the ovaries. Larger ovaries tend to have more eggs, while smaller ones may have depleted supplies.
It is important to note that ovarian reserve is only one factor among many for fertility. Women with a large ovarian reserve are more likely to get pregnant and to be able to carry a pregnancy to term. However, the eggs can still contain genetic variations that may cause birth defects incompatible with life. This often results in a miscarriage or a failure during implantation. Women who experience repeated miscarriages while attempting to get pregnant may be advised to consider genetic testing to see if there is a genetic issue that is causing pregnancy loss.
Infertility treatment typically starts conservatively with estimates of ovarian reserve and screening for common genetic conditions, as well as testing of a partner's sperm. As testing progresses, treatment recommendations can be made. If couples cannot conceive, care providers can make recommendations for additional treatments, including options such as using donor eggs or sperm, or a surrogate.