What Exactly is Antral Follicle Count (AFC)?

If you're considering or embarking on the path of egg freezing, you may have come across the term "Antral Follicle Count" (AFC) during your research. AFC is a crucial tool in assessing ovarian reserve and predicting the success of fertility treatments, including egg freezing. In this article, we delve into the world of AFC, exploring its significance, measurement techniques, and its role in optimizing your egg freezing journey.

In this comprehensive guide, we will walk you through the intricacies of AFC. We'll discuss what an antral follicle is, how AFC is measured, and what a normal AFC looks like based on age. Additionally, we'll explore the relationship between AFC and the egg freezing process, shedding light on how this information can guide and optimize your fertility journey.

What is an antral follicle?

Antral follicles are small fluid-filled sacs found within the ovaries that contain immature eggs. These follicles serve as the building blocks of our fertility. Each month, a group of antral follicles starts developing in response to hormonal signals. Among this group, one follicle becomes dominant and eventually releases a mature egg during ovulation.

How do you measure AFC?

There’s only one way to measure the antral follicle count: through a transvaginal ultrasound, which allows for a close examination of the ovaries. During this procedure, a specialized ultrasound probe is inserted into the vagina to visualize the ovaries and count the number of antral follicles present in both ovaries (the definition of antral follicles varies across fertility clinics. Some clinics count follicles that measure 2–10 mm in diameter, while others focus on follicles ranging from 3–8 mm). 

The AFC measurement is typically taken during the early follicular phase of the menstrual cycle when the antral follicles are at their most visible and measurable state. But it can be done anytime of the cycle.

What can an antral follicle count test tell you?

The antral follicle test holds a wealth of valuable information that can shed light on your reproductive health. So, what exactly can an antral follicle test tell you?

Ovarian reserve assessment 

The number of antral follicles detected during the test directly correlates with your ovarian reserve. This information can help your fertility doctor understand the quantity of follicles remaining in your ovaries in relation to your age. As we age, the number of antral follicles typically decreases, reflecting a decline in ovarian reserve. Understanding this relationship can help in making decisions about family planning and fertility preservation options. Learn more about ovarian reserve here.

How your body would respond to egg freezing

Antral follicles are a key determinant of how your ovaries will respond to ovarian stimulation during fertility treatments such as egg freezing. In fact, AFC correlates directly with the number of eggs retrieved at egg collection. By assessing your AFC, your healthcare team can tailor the stimulation protocol to optimize your chances of success.

Best timing for egg freezing 

The antral follicle count can also assist in determining the ideal timing for initiating fertility treatments. By assessing the AFC, your fertility doctor can guide you on the optimal time to start treatments, maximizing your chances of a successful outcome.

Premature ovarian failure (POF)

POF, also known as premature menopause, refers to the loss of ovarian function before the age of 40. Antral follicle testing can help in the diagnosis of POF by revealing a significantly reduced antral follicle count. A diminished AFC can indicate a decline in ovarian reserve, which is a characteristic feature of POF. This information is crucial in understanding the reproductive potential and considering appropriate fertility treatment options for individuals with POF.

Polycystic ovary syndrome (PCOS) 

PCOS is a common hormonal disorder that affects women of reproductive age. It is characterized by hormonal imbalances, irregular menstrual cycles, and the presence of multiple small follicles on the ovaries. Antral follicle testing plays a vital role in assessing PCOS by revealing an increased number of small antral follicles during the scan. This high AFC, along with other diagnostic criteria, helps in confirming the presence of PCOS and guiding appropriate management strategies.

The antral follicle test is a powerful tool in assessing your fertility health, but it is just one piece of the puzzle. It should be considered alongside other diagnostic measures and discussions with your fertility doctor to form a comprehensive understanding of your fertility health.

What is a normal AFC by age?

The normal range of antral follicle count can vary depending on your age. In general, younger women tend to have a higher number of antral follicles, indicating a larger ovarian reserve. As a woman ages, the number of antral follicles naturally declines, reflecting the diminishing ovarian reserve.

While the specific numbers can vary, a typical AFC for a woman in her 20s and early 30s may range between 10-20 follicles, in her late 30s around 8-15 follicles, and by her 40s, it could further decline to under 10 follicles. It's important to remember that these numbers are approximate and can vary based on individual factors such as genetics and overall reproductive health.

One study of infertile women looked at exactly how antral follicle count declines with age, finding the median AFC to be:

• 14 at age 25
• 12 at age 30
• 10 at age 35
• 8 at age 40
• 6 at age 45

AFC and egg freezing

When it comes to assessing ovarian reserve and predicting the number of eggs that can be retrieved during egg freezing, the antral follicle count (AFC) is a very helpful biomarker. It may even be the most important of ovarian reserve measures. A meta-analysis of 11 studies found that the AFC scan was as accurate as using multiple markers to predict ovarian response to stimulation. AFC outshined its counterparts like anti-Mullerian hormone (AMH) and follicle-stimulating hormone (FSH) as the predictor of ovarian response to egg freezing stimulation. 

So, when it comes to determining the potential success of your egg freezing journey, keep an eye on AFC. It can guide you through the uncertainties and help your healthcare team tailor the stimulation protocol to maximize your chances of a fruitful outcome. 

What does low AFC mean?

A low AFC can indicate a lower ovarian reserve and may have implications for fertility. When the AFC is low, it suggests that there are fewer follicles available in the ovaries, which can impact the number of eggs that can be retrieved during fertility treatments such as egg freezing.

But having a low AFC does not necessarily mean that pregnancy is impossible, but it may suggest that the response to ovarian stimulation during fertility treatments could be lower than average. With fewer follicles available, there may be a reduced number of mature eggs that can be retrieved for fertilization. This can affect the overall success rates of fertility treatments, as the quantity and quality of eggs play a crucial role in achieving a successful pregnancy now or down the line.

Remember that AFC is just one piece of the fertility puzzle, and other factors such as age, hormone levels, and overall reproductive health matter. 

What does high AFC mean?

A high AFC typically indicates a greater ovarian reserve and can be a positive indicator of fertility health. When the AFC is high, it suggests that there are a larger number of antral follicles present in the ovaries, which can potentially result in a higher number of eggs available for retrieval during egg freezing.

Having a high AFC is generally associated with a better response to ovarian stimulation during fertility treatments. With more follicles available, there is a greater likelihood of obtaining a larger number of mature eggs for fertilization. This can potentially increase the chances of success in achieving a pregnancy now or down the line.

A high AFC alone does not guarantee pregnancy or fertility success. Other factors such as the quality of the eggs, age, overall health, underlying reproductive conditions – as well as the health of the sperm – can also influence fertility outcomes. 

AFC is just one piece of the puzzle

The antral follicle count is a valuable tool in the realm of fertility assessment. By providing information about your ovarian reserve, it assists in predicting the response to ovarian stimulation and guides decisions regarding fertility preservation options like egg freezing. 

The AFC measurement, combined with other diagnostic tests and a thorough evaluation of an overall reproductive health, helps paint a comprehensive picture of your fertility health. Armed with this knowledge, you can make informed choices about your reproductive journey and take proactive steps towards preserving your fertility and achieving your family planning goals.

You are not a number

With all the nuances involved here, it’s important not to get lost in the weeds. Fertility is impacted by so many factors that you can drive yourself crazy trying to manage all of them. Remember, you are more than any number. This process can be overwhelming, but focusing on the things that you can control can help you feel more grounded during your fertility journey, whatever it may look like.

Cofertility is here to help you every step of the way on that journey.

Our Split program allows qualified people between 21 to 34 years old (with an AMH of 2+) to have the chance to freeze their eggs for free when donating half of the eggs retrieved to a family that can’t otherwise conceive.

Or, if you’re over 34, you can still participate in the Keep program up to age 40. In the Keep program, you’re able to freeze your eggs and keep them all for yourself, on your timeline. In addition, you’ll have access to our online support community, the Nest. This valuable resource lets you engage with other people freezing their eggs at the same time!

Whatever your journey looks like, our team is here to guide you through it and keep your family-building options open.

Sources:

• Antral Follicle. Science Direct. URL
• Verhagen TE, Hendriks DJ, Bancsi LF, et al. The accuracy of multivariate models predicting ovarian reserve and pregnancy after in vitro fertilization: a meta-analysis. Hum Reprod Update 2008;14:95–100. URL
• CAROLE GILLING-SMITH, STEPHEN FRANKS, CHAPTER 28 - Ovarian Function in Assisted Reproduction, The Ovary (Second Edition), Academic Press, 2004, Pages 473-488, ISBN 9780124445628, https://doi.org/10.1016/B978-012444562-8/50029-X. URL‍
• Almog B, Shehata F, Shalom-Paz E, Tan SL, Tulandi T. Age-related normogram for antral follicle count: McGill reference guide. Fertil Steril. 2011;95(2):663-666. doi:10.1016/j.fertnstert.2010.08.047 URL