The ovaries are where all of a woman’s eggs are stored. Each month, one egg is selected to grow and develop. The ovary releases this egg in a process known as ovulation. If the egg meets a sperm, then hopefully fertilization takes place, and a baby is born around nine months later! If ovulation is irregular or absent (i.e., an egg is not released regularly), then fertilization cannot take place.
Infertility can also result if there is an abnormally low number of eggs in the ovaries. Women are born with a given number of eggs. The female body cannot make new eggs. As a result, the number of eggs in the ovaries continually decreases as a woman ages. The number of eggs in the ovary is called the “ovarian reserve.”
Many tests can be performed to try to measure the ovarian reserve. Care must be taken with these tests because none of them is perfect. Also, none of the tests can tell us definitively if fertilization will be successful.
Some clinics use strict cutoff levels to determine if a patient is allowed to undergo fertility treatment. This can artificially increase a clinic’s success rates. If a clinic chooses to avoid treating women with significant ovarian reserve issues, then they are effectively screening out the patients with the lowest chance of success. This may make the clinic look good, but in actuality, they are falsely elevating their numbers.
At Advanced Reproductive Center, we do not use strict cutoffs. This is because we believe that each patient is an individual and must be treated as such. We treat patients, not numbers, and care is individualized based on each specific situation.
The most common tests to evaluate the ovarian reserve are baseline FSH level, AMH level, and antral follicle count.
Follicle-stimulating hormone (FSH) is the hormone that causes the eggs in the ovary to grow and develop. If the number of eggs in the ovaries is low, the brain produces more FSH to try and “push” the ovaries harder.
We can measure FSH early in the menstrual cycle. If it is elevated, then it is a sign that the number of eggs in the ovaries is low. Low egg numbers may lead to difficulties in trying to get pregnant.
It is important to remember that it is the low egg number that is the problem. The FSH is just a marker telling us that the egg number is low. Patients sometimes ask if we can correct the FSH level. The answer is yes; we can give estrogen, which will force down the FSH level. While the FSH level will be lower, this will not fix the problem because the number of eggs in the ovaries will still be low. Unfortunately, while we can manipulate the FSH level and make it look like things are better, we cannot put more eggs in the ovaries and genuinely fix the problem.
Anti-Müllerian hormone (AMH) is a hormone that is produced by the small resting follicles in the ovary. Each follicle contains one egg. The more follicles, the more eggs. Therefore, we can measure AMH to get an idea of how many eggs are in the ovary.
The higher the AMH level, the more eggs there are in the ovaries. The lower the AMH level, the lower the number of eggs in the ovaries.
Care must be taken in interpreting AMH levels. AMH is a newer test, and as such, it is not as well understood as FSH. It is a good test and a useful test, but like all ovarian reserve tests, it is not perfect.
Antral follicle count (AFC) is performed during a transvaginal ultrasound. During the ultrasound, we can count the number of small resting follicles in the ovaries.
There is a relationship between the number of small resting follicles in the ovaries and the total number of eggs in the ovaries. The higher the AFC, the higher the number of eggs in the ovaries, and the lower the AFC, the lower the number of eggs in the ovaries.
AFC is a quick and easy test that can be done anytime a transvaginal ultrasound is performed. AFC can also be useful in trying to predict how a person will respond to fertility drugs. However, just like the other ovarian reserve tests, its ability to determine who will or will not conceive is far from perfect.