A Guide to Antral Follicle Count

The eggs produced by ovaries are contained within tiny fluid-filled sacs called antral follicles. They are central to ovulation as they are in essence the ‘protective housing’ where immature eggs develop fully before they are released. 

The  number of follicles produced in any individual within any cycle varies from person to person. Let us discuss antral follicle count and why it matters when it comes to assisted reproduction treatments. 

Antral Follicle Count

A person’s ability to become pregnant naturally is determined by their antral follicle count. When antral follicles begin developing, they do so in groups. In typical menstrual cycles,  only one of these follicles will reach maturity at each cycle.

During assisted reproduction treatment, more than one egg is typically required, in order to increase the chances of success. As a result, it is key to determine how viable a person’s antral follicles are. 

Several factors are considered, as they affect both the potential number of follicles produced during treatment as well as their quality. The main factors are:

Age

The number of follicles produced in the ovaries decreases with age meaning that a person’s likelihood of becoming pregnant also decreases with each cycle. Additionally, the quality of eggs being produced in the ovaries also declines.

Health

Physical health directly affects the viability of a person’s antral follicles. Lifestyle, Body Mass Index (BMI), tobacco, drugs, and alcohol use all have an impact on the health, quantity and quality of the antral follicles. 

Medical History

A history of disease and medical conditions such as hypertension, periodontal disease, chlamydia, PolyCystic Ovary Syndrome (PCOS), and endometriosis, contribute to antral follicle viability. As well chemotherapy and radiation treatments, each of which can sometimes cause infertility. 

The Antral Follicle Count (AFC) Test

The quantity of immature eggs (oocytes) a person has left in theor ovarian reserves is determined through an AFC test, which gives a general estimate. This information is used in deciding the most appropriate assisted reproduction treatment for that person.

The procedure typically takes a few minutes and involves the use of a transvaginal ultrasound to capture images of the ovaries, which are then sent to a specialist for interpretation.

Healthcare practitioners are then able to see the development of antral follicles, and also assess how, based on age and lifestyle, one’s AFC compares against normal ranges.

Normal Vs. Abnormal AFC

A normal AFC varies from person to person. One study showed that  before a person reaches the age of 37,  there is a decline of almost five percent annually in the production of antral follicles. Further, this rate more than doubles thereafter.

Another study showed that with a higher number of antral follicles, people produced a higher number of eggs during ovarian stimulation, in assisted reproduction treatments.

The general range of AFC by age is outlined below:

Follicles and Menstruation

The development and maturation point of antral follicles determine when a person can get pregnant, if at all. The follicular phase of a menstrual cycle - beginning right after the end of menstruation - is when antral follicles begin to develop in preparation for fertilization. 

This phase usually lasts about two weeks, within which a follicle matures and is released - a phase called ovulation. Ovulation takes place typically about two weeks before a person gets their period, and it is during this phase that the egg can be fertilized, leading to pregnancy. 

It is not known the exact moment when a follicle matures and is released, and therefore pregnancy is possible outside of the ovulation window.

Follicles in Fertility Treatments

To increase the chances of fertilization and positive outcomes for embryos, fertility treatments typically require more than the singular mature follicle released monthly. 

Oral medications as well as hormonal injections are thus prescribed to stimulate the ovaries into producing more antral follicles, while simultaneously causing more follicles to mature each cycle. 

Intrauterine Insemination (IUI)

IUI treatments usually require one mature follicle. During the hormone treatments however, more than one follicle could mature. Another AFC test would be required before the IUI treatment begins to ascertain the actual numbers.

Although the chances are low, multiple pregnancies have been known to occur using IUI, so if more than three mature follicles are present, often the IUI procedure would be cancelled in order to prevent risks during pregnancy. 

In Vitro Fertilization (IVF)

The results from the AFC tests are tyoicallg by professional  healthcare providers to determine how the hormonal phase of treatment will proceed. IVF typically requires about 10 - 15 follicles per round. 

Because IVF involves extracting mature follicles from the ovaries and fertilizing the eggs outside the uterus, the stimulation of multiple follicles provides individuals with a potentially larger number of eggs that can be fertilized right away, or frozen for future treatments. 

To Conclude

Whether through assisted reproduction technologies or through traditional means, without antral follicles there is no pregnancy. Antral follicle count plays a crucial role in determining fertility and the likelihood of a person becoming pregnant. 

It is important to note that a low AFC is not a deterrent to a healthy pregnancy, and therefore tye greater focus should be placed on the health of the follicles themselves. Individuals who had healthier antral follicles to begin with, typically go on to have healthy pregnancies, despite declined antral follicle production.       

Frequently Asked Questions (FAQs)

What is a transvaginal ultrasound?

A transvaginal ultrasound is a medical imaging procedure that uses an ultrasound shaped like a wand. It is typically inserted into the vagina, allowing for the pelvic cavity, including the uterus, fallopian tubes, and ovaries to be examined.

Is IVF better than IUI?

There are many factors that go into deciding a treatment plan. It is therefore best to consult with your healthcare provider to help you select the treatment that would work best for you.

Why is my AFC low?

There could be a myriad of factors affecting this outcome. In order to know more, speak with your healthcare provider to determine which specific factors have contributed to your low AFC, and they will advise you on what can be done about it.

Can I increase my AFC?

The number of follicles your body produces at each cycle is unique to you. It is important to understand that hormonal treatments used in assisted reproduction do not increase the number of follicles, rather, of the total number of follicles produced naturally, hormonal treatments increase the number of those that reach maturity.