How many eggs do I have left? Understanding ovarian reserve testing.

While there is no exact way to measure or quantify how many eggs a female has left, there are certain ovarian reserve tests that are used in practice to help gauge a female’s fertility. These tests can help a female understand her egg quantity compared to other women that are of similar age. As a fertility specialist, I like to reference if a female’s ovarian reserve tests are average for her age, above average for her age, or below average for her age.

So lets talk about three most commonly utilized tests.

1. Anti-mullerian hormone (AMH)

AMH is a hormone that is made in the ovary (specifically by cells called granulosa cells, which function to nourish and support a woman’s eggs). When a women has more eggs within her ovaries, there will be more granulosa cells producing more AMH.

When the AMH is low, this is concerning for diminished ovarian reserve (or a decline in egg number). When the AMH is high this may predict a higher than average egg number, or it can be associated with another condition called polycystic ovary syndrome (PCOS). There are age related averages for AMH that help women understand if they are above average for their age, average for their age or below average for their age.

Additionally, AMH values are important in fertility treatments for women. They help determine the dosing of certain hormone medications for either an IVF cycle done for infertility, or the dosing of hormones for women who are completing an egg freezing cycle.

You can determine your AMH level through a simple blood test. This information can help you be proactive and make appropriate choices for your future fertility. For example, if you are not currently planning to start a family, and your AMH is lower than average for your age, it could prompt you to consider egg freezing or embryo freezing.

There are good studies that indicate that AMH does not predict your ability to have a child. For example, if your AMH is low for your age, this does NOT mean that you cannot get pregnant or that you will be or are infertile. It is just a measure of your ovarian reserve, based on the active pool of follicles within your ovaries.

2. Antral Follicle Count (AFC)

The AFC can be assessed using a transvaginal ultrasound and only takes a few minutes to complete. Ideally, it is done in the early phase of the menstrual cycle, called the follicular phase. However, you can still assess the antral follicle count on any day of the mentrusal cycle and gaine instignt into a womeans’ feriliyy.

Ovary with Antral follicles visible

What are Antral Follices? They are small fluid filled sacs (2-10 mm in size) that appear as black little circles on a pelvic ultrasound. Each folicle contains on egg that has already undergone 1-2 months of maturation within the ovary (and can now be seen on ultrasound). The AFC dose not represent the total number of eggs, rather what is the number of potential eggs available in this currnt cycle.

Women who have more visible antral follicles typically have greater ovarian reserve and women who have a decline in their antral follicle count typically have a lower ovarian reserve. This is important because an antral follicle count can help in understanding a women’s fertility potential and can help physicians determine the ideal fertility treatments and success with those treatments.

The AFC can vary cycle to cycle by about 10-20%. Therefore, there are months where counts can be higher and some months that the count is lower. In women who are planning to do IVF, it is best to start the cycle when the count is o the higher end of if possible. Also, there is some variability in how different providers assess the AFC (termed interobserver variability)

Women with PCOS tend to have a high antral follicle count and sometimes this information is used to aid in the diagnosis of PCOS. But it is important to keep in mind that young women who have a high ovarin reserve (egg number) may have a high AFC which is completely normal and this does not meanthey have PCOS (rather they have polycystic ovaries).

3. Follicle Stimulating Hormone (FSH)

FSH is a hormone made by the pituitary gland in the brain, that is useful in assessing a female’s ovarian reserve. Additionally, it is useful in determining the cause of irregular menstrual cycles.

FSH, as the name suggests, simulates the growth of follicles within the ovary. These follicles in term produce the primary hormone called estrogen.

At baseline, women produce a level of FSH that will typically stimulate one follicle to grow and become the dominant follicle in the cycle. As this follicle grows, the granulosa cells surrounding the egg will make the hormone estrogen. Once a threshold estrogen level is reached, this stimulates the surge of another hormone called luteinizing hormone or LH which precedes ovulation.

FSH should be checked on day 2 or 3 of the menstrual cycle and should always be checked in conjunction with an estradiol level. If the estradiol level is high at the start of the cycle (which is not normal), then the FSH will be suppressed (and appear lower than it should). If this occurs the FSH and estradiol level should be repeated the following cycle.

A normal baseline FSH level is less than 10.

An elevated FSH level could be indicative of diminished ovarian reserve or that a woman may be nearing menopause.

Typically, FSH levels will range between 4-8 in women of 25-40 years of age.

Very low FSH levels and irregular menstrual cycles or the absence of a period could be concerning for a condition called hypothalamic amenorrhea.

In summary:

there are three measures of ovarian reserve: Anti-mullerian hormone (AMH), Antral follicle count (AFC), Day 2 or 3 Follicle stimulating hormone (FS). Neither of these can identify or quantify exactly how many eggs a female has. These tests instead can provide a status in terms of ovarian reserve at this moment in time.

These tests so NOT predict the future. These tests only assess the status at this moment in time. They All women have a decline in their ovarian reserve and egg number year after year. These tests give you a glimpse or snapshot into your reserve at this moment in time. All women have a decline in ovarian reserve and egg number year after year and therefore, having a high AMH now does not mean that your AMH will remain high in 2 years.

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