Antral Follicle Count: What It Is & Normal Counts by Age

The antral follicle count is a simple but important test that tells you how likely you are to conceive.

Whether you’re just starting to think about family planning, considering freezing your eggs, or are beginning IVF, here’s everything you need to know about antral follicles, how they’re counted, and what the results can—and can’t—tell you about your fertility.

Antral follicles are small, fluid-filled sacs in your ovaries that each contain an immature egg, usually measuring between 2 and 10 millimeters in diameter. 1

You’re born with all the ovarian follicles you’ll ever have (between one and two million). As you grow up, they naturally decline in number. By the time you reach puberty, you have around 300,000 left, or about 25% of your original count. 2

How antral follicles affect your fertility

As part of your menstrual cycle, your body produces something called follicle-stimulating hormone (FSH). Each month, it causes a group of follicles to start developing eggs.

While many follicles develop eggs, typically, only one follicle becomes “dominant” and releases a mature egg when you ovulate. The rest of the follicles in that monthly cohort simply disintegrate.

Antral follicles are the ones that grow large enough to be seen on an ultrasound. The more of these you have, the more fertile you probably are (even though, again, only one follicle generally releases an egg).

Counting your antral follicles allows doctors and fertility specialists to assess your ovulation and overall chances of getting pregnant.

Your doctor will use a transvaginal ultrasound to measure your AFC. Unlike the kind of ultrasound you get when you’re pregnant (where a wand is moved across your abdomen), this procedure involves gently inserting a slender, specialized ultrasound probe into your vagina.

Your sonographer or doctor will carefully examine each one of your follicles and count the number of visible antral ones.

The total count from both ovaries gives you your AFC for that cycle. Your doctor will usually perform the scan in the early part of your menstrual cycle (days 2–5), when your follicles are most visible. 3

Is the AFC test painful?

A transvaginal ultrasound might sound intimidating, but it’s a quick and generally painless procedure. It may feel a little uncomfortable when your sonographer moves the wand around; let them know if that’s the case. The sonographer may be able to change positions if it does cause you discomfort. 4

Your AFC will give you and your doctor a detailed look at your overall fertility.

Gauging your ovarian reserve

Perhaps the most important insight you can get from the AFC is about your ovarian reserve. This is the number of eggs you have left in your ovaries. A higher AFC generally means you have more chances of producing viable eggs, while a lower count indicates a diminished reserve. 5

Since your ovarian reserve naturally declines with age (more on this later), your AFC will show your doctor where you are on your reproductive timeline.

Predicting your response to fertility treatments

Your AFC also will help your doctor predict how well you’ll respond to fertility treatments like in vitro fertilization (IVF) or egg freezing. 6

If you opt for IVF, your doctor will give you stimulation medications that encourage your body to produce mature eggs. If your AFC is higher, it often means your ovaries will respond well to these medications. This could allow your doctor to retrieve more eggs during a single cycle. 7

On the other hand, your doctor may not be able to retrieve as many eggs if you have a lower AFC. Knowing your AFC lets your doctor plan how much medication you’ll need.

Diagnosing certain conditions

Your AFC can also be a clue in diagnosing hormonal conditions. An unusually high AFC can be a sign of polycystic ovary syndrome (PCOS), a condition where multiple small follicles develop on your ovaries. 8

On the flip side, a very low AFC for your age can be an indicator of premature ovarian insufficiency (POI), also known as premature ovarian failure. This diminished reserve isn’t a part of normal aging and can be caused by diseases or lifestyle factors like smoking. 9

Your antral follicle count will tell you about the quantity of your potential eggs, not their quality. A high count doesn’t guarantee that your eggs are genetically healthy, and a low count doesn’t mean your remaining eggs are poor quality.

Note that a low AFC is not a deal-breaker for getting pregnant naturally. As long as you’re ovulating regularly, your body is still selecting one egg each month. The total number of follicles in reserve doesn’t significantly impact your ability to conceive naturally in any given cycle.

While every person is different, there are general trends in the number of antral follicles women have as they get older.

Here are the mean (average) AFCs of women at different ages: 10

There’s a clear trend that your AFC begins declining much faster once you reach your 30s. However, because these figures are just averages, your own number might vary.

What a low AFC actually means

Before you spend too much time ruminating over your number, remember that a low or high count isn’t necessarily “good” or “bad.”

With that said, a low AFC (which generally means one under 7, depending on age) suggests that you have a diminished ovarian reserve. 9 That does suggest that you might have fewer years remaining during which you can get pregnant than someone with a higher count.

If you’re undergoing fertility treatments like IVF or egg freezing, your doctor may also want to give you a higher dose of stimulation medication to maximize the responses of your available follicles.

Your AFC is a valuable piece of data, but the number you get from it isn’t necessarily set in stone. Several factors can influence the count, which is why many doctors look at it alongside other markers like AMH.

Some of these factors include:

Ultrasound limitations and technician skill

Counting follicles is a manual process that relies on the sonographer’s skill. The ultrasound provides a 2D image of your 3D ovaries, and sometimes, follicles can hide behind others or be otherwise difficult to see.

As a result, your count may vary slightly from one test to another (and one clinic to another), depending on the technician’s skill.

Cycle-to-cycle fluctuations

Your AFC can also vary slightly from one menstrual cycle to the next. During an IVF or egg freezing cycle, for instance, your follicle count may increase after you start taking stimulation medications. These hormones help previously “sleeping” or smaller follicles grow, making them more visible on the ultrasound.

Hormonal medications

If you’re on hormonal birth control, your AFC will probably appear temporarily suppressed. These medications are designed to prevent follicular development, so they keep your follicles in a resting state.

This is not a reflection of your true ovarian reserve. For the most accurate baseline reading, your doctor may recommend pausing hormonal contraceptive use for a cycle or two before the scan.

Knowing your AFC is a good starting point for understanding your fertility, especially if you’re considering IVF or egg freezing.

However, your AFC isn’t a crystal ball, and it doesn’t have the final say on your ability to start a family. Rather than stressing too much over a number, focus on leading a healthy lifestyle and working with your doctor to give yourself the best chance of conceiving.