How Many Ovarian and Antral Follicles You Should Have for Fertility?

1. 🩺 What are antral follicles?
2. 🤰 How many follicles are needed for infertility treatment?
3. ⭐ Pregnancy prospects with reduced ovarian reserve
4. 💊 Stages of folliculogenesis
5. ✔ Role of follicles in the menstrual cycle
6. 📝 Follicles required on hormonal preparations
7. ⚡ Follicles required for IUI
8. 🧬 Follicles needed for an IVF cycle
9. 🩺 Antral follicle count test (AFC)

The results will give a clear picture of the prospects for pregnancy: naturally or with the help of IVF. Let us look at the issue in more detail, considering the functioning of the ovaries and the influence of the follicular reserve on conception.

What are antral follicles?

In order to estimate your chances of getting pregnant, you need to understand how many eggs left in you. Their number is constantly decreasing: if in adolescence there are about 300-400 thousand, then at the age of 30 - 100-150 thousand. Despite the seemingly large numbers and participation in the conception of 1-2 eggs, this is a problem: most oocytes die before reaching maturity, on average, 10-20 pieces die every day.

The eggs are located in the follicles located in the ovaries, therefore, to estimate their number, it is necessary to count the number of follicles.

It is possible to count the number of follicles in the ovaries at the moment they reach a certain stage of maturity. The AFC method, implemented with the help of ultrasound, helps the doctor in this. In order to understand when the desired stage comes, let us look at the process of their development.

Stages of folliculogenesis

The development of follicles includes 6 phases, each of which solves its own task:

1. Primordial: found in the ovaries of the newborn.
2. Primary: Several primordials become primary each day from puberty to menopause.
3. Secondary: Theca cells that produce hormones are added to the primary ones.
4. Tertiary (antral): contain an antrum - a cavity filled with fluid.
5. Graafian follicle: a follicle of sufficient size for ovulation. Only 1 or 2 of the total will reach this stage in each menstrual cycle. The size varies from 18 to 25 mm.
6. Luteal corpus: formed from an open follicle that has released an egg.

Formation begins in the ovary with microscopic primordial follicles, 0.025 mm in size. Every day, under the influence of hormones, they “wake up”, mature and increase in size.

In the tertiary stage, an antrum is formed in some follicles - a cavity filled with fluid. They are called antral. Their diameter varies from 2 to 10 mm. At this stage, they can already be visualized on ultrasound. The dynamics of maturation is usually monitored in three stages: on days 2-5 of the menstrual cycle, 12-14 and 3-5 days before the end of the cycle.

Antral follicle count test (AFC)

Let us take a closer look at the counting process. Purposefully, this method is resorted to before the treatment of infertility. On days 2-5, an ultrasound is performed, during which the doctor examines each ovary and counts the number of follicles ranging in size from 2 to 10 mm. The test results give the following data:

• Ovarian reserve;
• Diagnosis of primary ovarian failure;
• Diagnosis of polycystic ovary syndrome (PCOS);
• Age-specific fertility assessment (number of follicles compared to women in your age group).

How many antral follicles is normal?

In general, numbers between 3 and 6 are considered low. According to research results, the number of active antral follicles correlates with the number of oocytes. If there are few of them, this may indicate a low ovarian reserve.

The number of antral follicles calculated from a study of healthy fertile women is as follows:

• 25-34 years old: average - 15, minimum - 3, maximum - 30;
• 35-40 years old: average - 9, minimum - 1, maximum - 25;
• 41-46 years old: average - 4, minimum - 1, maximum - 17.

An additional assessment method is the anti-Mullerian hormone (AMH) test. Antral follicles provoke a higher level of it in the blood. The analysis is convenient as it can be carried out on any day of the cycle.

A small number of follicles does not mean the impossibility of getting pregnant. However, there is a possibility that in the treatment of infertility, the ovaries may be less responsive to hormonal stimulation than in women with normal indicators.

Repeated ultrasounds in case of poor results are recommended to exclude the influence of the qualifications of the doctor and equipment on the diagnosis.

A low ovarian reserve in women under 40 may be a sign of primary ovarian failure, and an abnormally high ovarian reserve may be PCOS.

Role of follicles in the menstrual cycle

The menstrual cycle includes two phases: follicular and luteal. During the first one, antral follicles prepare for ovulation. If a woman undergoes a course of infertility treatment, then under the influence of drugs, not 1-2, but 8-15 pieces mature and ovulate.

The follicles themselves have several functions:

• Nutrition and protection of the egg in the process of its development;
• Production of reproductive hormones;
• Transformation into corpus luteum after ovulation. Its function is to secrete progesterone, a hormone that maintains the lining of the uterus. This is a necessary condition for the implantation of the embryo.

The beginning of the follicular phase is the first day of menstruation. The production of follicle-stimulating hormone (FSH) begins, which starts the process of maturation of the follicles. After their increase, estrogen production increases, and FGS slows down. This allows you to slow down the growth of small follicles, while 1-2 will increase in size. They will subsequently release an egg. After 1-2 follicles become dominant and begin to produce even more estrogen, the rest will fall apart. Elevated level of estrogen will cause the production of luteinizing hormone (LH), which will allow you to complete the phase and start ovulation (egg release).

The luteal phase is the period from ovulation to the onset of pregnancy or the next menstrual cycle. In the context of infertility treatment, it involves taking hormonal drugs to support the process of embryo implantation and the development of gestation.

How many follicles are needed for infertility treatment?

The required number of follicles varies depending on the method of fertility treatment. In the case of IVF, an average of 8 follicles, 13-20 mm in size, is considered sufficient. Of these, you can get 8-15 eggs of different quality.

Follicles required on hormonal preparations

Against the background of taking hormones, a good result will be getting 1-2 large follicles. Each mature follicle can release a good quality egg that can be fertilized.

However, it should be understood that ovulation does not guarantee pregnancy: you can become a mother of twins if two eggs are released and fertilized. You can become a mother of one child. Or pregnancy may not happen for a variety of reasons, which will need to be established by further examinations.

Follicles required for IUI

As in the previous case, 1-2 mature follicles are enough. With a course of hormones, there is a risk of multiple pregnancy, because 3-4 or more follicles can mature. In the case of 4 or more follicles, the doctor may decide to cancel the IUI procedure and / or prohibit sexual contact.

Important: If your doctor tells you to avoid sexual intercourse, follow this prescription. Sexual contact with so many follicles can result in triplets or even higher order pregnancies. This carries a huge risk to your life and the life of your children. You can always repeat the course of treatment in the next cycle.

Follicles needed for an IVF cycle

Depending on your situation, 8 to 15 follicles may be required. Eggs will be obtained from them by aspiration with a special needle under ultrasound control. Not necessarily all of them will be suitable for creating an embryo. Only those that have no visible damage will be selected. Their number may be much less than the number of follicles.

Pregnancy prospects with reduced ovarian reserve

As already noted, a low AMH level is a marker of reduced ovarian reserve. Normal values for women (ng / ml):

• up to 35 years old - 4-6.8, the lower threshold of the norm - 2.2-4,
• for women 35-40 years old - 2.1-1.0,
• after 40 years old is less than 1.0.

Even with low (less than 1 ng / ml) and critically low (less than 0.2 ng / ml) rates, a woman still has a chance of pregnancy in a natural way.

If the AMH values are in the range from 0.9 to 0.2 ng / ml, it is necessary to pay attention to the FSH level. If FSH is within 1.37 mU/ml, then the chance of natural conception is preserved.

In the case when AMH is less than a critically low value, use of donor eggs is prescribed.

Feskov Human Reproduction Group in its reproductive programs uses the latest methods of infertility treatment to ensure pregnancy using the woman's own eggs.

If the ovaries respond to hormonal stimulation, there is a chance to get some good quality eggs. At the same time, we select healthy spermatozoa to create embryos from your genetic materials.

The created embryos undergo a pre-implantation genetic diagnosis (PGD) procedure, which helps to select those that have the highest potential for implantation for the IVF program.

We will conduct a full examination and, if necessary, treat you to exclude factors not connected with low ovarian reserve that could prevent you from carrying a pregnancy. If your chances of successful gestation are low and / or cannot be corrected, surrogacy may be the way out. We have a huge database of surrogate mothers, among them there is definitely a woman worthy of your trust.

Feskov Human Reproduction Group implements guaranteed programs: by paying for our services you will get results in 100% of cases. The clinic will perform as many IVF cycles as needed for you to become a mother: on your own or with the help of a gestational carrier. In case of unsuccessful IVF or termination of pregnancy, we will repeat the program at our own expense as many times as necessary for the birth of a baby.

We will do everything we can to make sure your baby is born, ideally using your oocytes. If your situation does not allow this, you will be able to choose a donor who is as phenotypically similar to you as possible.

Request a free consultation with doctors on our website: tell us about your situation, and we will suggest possible ways to have a baby in your individual case.

Authors, contributors:

Irina Feskova
Reproductive endocrinologist, medical director

published: 28 September 2023
updated   : 29 September 2023

share page with: