I met this eminent reproductive endocrinologist from Europe at a conference and we were discussing low egg reserve and he verbalized what reproductive endocrinologists always knew but in a very clear statement ” you cannot create a reproductive potential for a woman, a good reproductive endocrinologist can take a woman and get her to the maximum of her ovarian potential and IVF success” This issue comes often into discussions of success rates of fertility treatment in general, fertility preservation, egg freezing, ovarian tissue freezing and any other topic related to the success of achieving and maintaining a pregnancy, even if the cause for sub-fertility is related to the male partner.
Ovarian reserve is defined as the number and quality of eggs remaining in the ovary. It corresponds to fertility potential in women. Many scientists were fascinated with the ovary and were interested in predicting the number of eggs at a given age. One such model is shown here.
It was realized however, that there are considerable individual variations among women of the same age due (between the orange and green lines in the figure) to genetic and other factors. In other words tools other than age are always needed to better predict ovarian reserve, fertility potential and success of treatment. A large group of tests were developed. Will discuss the most informative ones here.
FSH (follicle stimulating hormone). A hormone that is produced by the master gland in the brain and controls the development of follicles (the units that contain the eggs) in the ovary. As the number of follicles decrease, FSH increases. Levels on the second or third day of the cycle reaching 12-15mIU/mL or higher were found to associated with reduced chance for successful fertility treatment.
Ultrasound scan for antral follicle count. Ultrasound scan early after menses can identify small follicles within the ovaries. This gives an immediate impression of ovarian reserve. Low numbers e.g. < 10 in both ovaries indicate low reserve.
Antimullerian hormone (AMH). Its a hormone produced by the cells surrounding the egg. It can be tested at any day of the cycle. Levels < 1ng/mL generally indicates low reserve.
Two precautionary notes; 1. Abnormal value of these or other tests does not automatically indicate that a woman should be prevented from trying using her own eggs. The predictive ability of these tests is modest and not absolute (these tests can make mistakes) 2. Theses tests interact with other factors as age. Younger women with high FSH have higher success rates than older women with similar value. The results of these tests should be carefully interpreted by a reproductive endocrinologist. Generally women should not be denied treatment based on the test result alone. These tests have low ability to predict the occurrence of pregnancy.
Egg quality. In short it means the egg has finished reduction division with appropriate number (23) and structure of its chromosomes. Tests for ovarian reserve cannot directly predict the quality of individual eggs or embryos. Age is a better predictor of egg quality. Invasive tests were developed to detect the number and structure of chromosomes in the egg (normal 23) or embryo cells (normal 46). So far there is no proof that any of these tests is 100% accurate nor there is proof that they improve outcomes of fertility treatment.
What are the benefits of testing for ovarian reserve?
1. For women: to have some insight into the chances for success of their fertility treatment
2. For their reproductive endocrinologists: to be able to tailor fertility treatments to improve success rates. Low ovarian reserve may require modification of fertility medication to improved response.
3. In fertility preservation: the success of preservation is especially related to egg reserve. In the majority of cases, freezing of eggs and embryos for preservation of fertility. For example, women with low egg reserve will produce small number of mature eggs after stimulation. Because some of the eggs will not survive thawing, they will end with small number of embryos available for transfer. Some physicians prefer to restrict egg freezing or ovarian tissue freezing to women younger than 40 with normal reserve.
4. In women exposed to chemotherapy: exposure to cyclophosphamide and other agents markedly reduce egg reserve. Evaluation of ovarian reserve may reflect fertility potential after cancer treatment. Very young women exposed to less toxic treatments may preserve their future fertility after cancer treatment. Markers of ovarian reserve are however, may not accurately reflect damage caused by chemotherapy. Women with normal ovarian reserve after chemotherapy commonly exhibit low response to fertility medications.
Read more about ovarian reserve and low response to ovarian stimulation in my review