Many women are interested in questions about what a follicle is and what its role is in pregnancy. Below, we provide the most important information about this process:
1️⃣ A follicle is the place where a female egg cell matures. It is the starting point of life, where the foundation for the formation of the future fetus is created.
2️⃣ A healthy follicle is the guarantee of a healthy pregnancy. If you have any doubts regarding conception, it is recommended to undergo a special follicle test under medical supervision.
3️⃣ After the age of 30, the number of follicles decreases. The reserve of egg cells in a woman's body is limited, so it is very important to undergo medical examinations in a timely manner.
4️⃣ Dozens of follicles wake up every month, but only one matures. The strongest follicle reaches the dominant level, while the others fade away.
5️⃣ Follicle growth can be determined via ultrasound. With the help of folliculometry, it is possible to monitor the maturation of the follicle and receive precise specialist advice on what to do for follicle rupture.
What is a follicle?
As we briefly mentioned above, a follicle is a fluid-filled sac located in the ovary, inside which an egg cell matures. It acts as a natural shell that protects the egg cell and matures it until ovulation. It is inside the follicle that the starting point of life — the foundation for the future fetus — is created.
The follicle is not limited to protection alone: the female sex hormone, estrogen, is produced in its wall. As the egg cell matures, the follicle also grows and enlarges. Therefore, the short answer to the question of what a follicle is: it is the most fundamental link in a woman's reproductive system, on which the ability to have children directly depends.
What is a dominant follicle?
Dozens of follicles wake up every month, but usually only one fully matures — this largest and most mature follicle is called the dominant follicle. The remaining follicles undergo atresia, meaning they stop growing and are reabsorbed.
During ovulation, the dominant follicle can reach a size of up to 2 cm (20 mm) and is often located in the right ovary. It is this follicle that ruptures, releasing an egg cell ready for fertilization. If the dominant follicle does not mature, ovulation does not occur — and this becomes an obstacle to pregnancy.
Types of follicles
A follicle matures through several stages, and at each stage, it has its own name:
Primordial follicle — the very first, "dormant" stage; it forms while the girl is in the womb and is stored as a reserve (ovarian reserve).
Antral follicle — forms around the 7th day of the menstrual cycle, begins to secrete estrogen, and increases in size.
Preovulatory (Graafian) follicle — the final stage; the dominant follicle prepares for ovulation, and the volume of fluid inside increases several times over.
Female follicle — result of a gynecological ultrasound examination
What is follicle rupture?
Follicle rupture is the process where the wall of a mature dominant follicle breaks, releasing the egg cell. This phenomenon is called ovulation and is one of the most important moments for becoming pregnant. The egg cell leaves the follicle, enters the uterine cavity, and becomes ready for fertilization there.
When does follicle rupture occur?
In an average 28-day menstrual cycle, the day of follicle rupture (ovulation) falls approximately on the 14th day. However, this number is approximate: depending on the length of the cycle, follicle rupture can occur between the 11th and 16th days. Before rupture, the follicle size usually reaches 18–25 mm.
What are the signs of follicle rupture?
Many women can feel the signs of follicle rupture. The most common symptoms are:
mild pulling pain in the lower abdomen (often on one side);
an increase in the amount of vaginal discharge and its becoming clearer;
a slight rise in basal body temperature;
increased sexual desire (libido);
sometimes, increased sensitivity of the mammary glands.
The most reliable method for determining the exact day of rupture is a folliculometry examination.
What should be done for follicle rupture?
If a follicle matures but does not rupture, this becomes an obstacle to pregnancy. In such a case, one should not take medication on their own. Only a doctor can prescribe the necessary treatment for follicle rupture — for example, special injections to stimulate ovulation — based on the results of an ultrasound (UZI) and hormonal tests.
What is the reason for a follicle not rupturing?
The failure of a mature follicle to rupture is one of the common causes of infertility. The main reasons are:
thickness of the follicle wall — the shell is too thick, and the egg cell cannot exit;
hormonal imbalance — deficiency of luteinizing hormone (LH);
persistence — the follicle matures normally but does not rupture, remaining throughout the entire cycle;
inflammation of the ovaries (acute or chronic);
stress, nervous tension, and extreme diets.
Follicle norm: how many follicles should there be?
The follicle norm depends on the woman's age and the day of the menstrual cycle. Approximate indicators when an ultrasound (UZI) examination is performed on the 7th day of the menstrual cycle:
7–16 follicles — good probability of pregnancy;
4–6 follicles — low probability of pregnancy;
less than 4 — very low probability of pregnancy.
On the 7th day of the menstrual cycle, 6–10 antral follicles are normally visible; by the 10th day, one becomes dominant and stands out, while the others are reabsorbed.
What does it mean if there are many or few follicles?
If more than 10 follicles are visible in the ovary, this is called a multifollicular or polyfollicular condition and is often associated with polycystic ovary syndrome (PCOS). Conversely, very few or no follicles may indicate a reduced ovarian reserve or early menopause. After the age of 30, the number of follicles naturally decreases.
Follicle size during the menstrual cycle
In each cycle, the follicle grows gradually. Approximate size:
Until day 7: ~5–6 mm;
Day 8–10: dominant follicle ~10–15 mm;
Day 11–14: 18–25 mm, ready for ovulation;
Larger than 28–30 mm: may indicate the formation of a follicular cyst.
What is folliculometry?
Folliculometry is a method of monitoring the maturation and rupture of a follicle via ultrasound (UZI) over several days. It is with the help of this examination that the size, number, and day of ovulation of the follicle are precisely determined.
How is folliculometry performed?
The examination usually begins on the 7th day of the menstrual cycle and is repeated several times:
Day 7: follicles are small, 5–6 mm;
Day 11: follicle is 10–12 mm, the dominant follicle can be identified;
Day 12–14: follicle is 18 mm and larger, ovulation is near;
After day 14: it is confirmed whether the dominant follicle has ruptured or not.
Folliculometry plays an important role in determining the cause of infertility, setting the day of ovulation, and preparing for the IVF (extracorporeal fertilization) process.
When to see a doctor?
It is recommended to consult a specialist in the following cases: if the menstrual cycle is irregular (shorter than 21 days or longer than 35 days); if pregnancy has not occurred for more than a year; if signs of ovulation are not felt; if previous examinations have detected that the follicle does not rupture or mature.
💬 If you are planning a pregnancy, monitoring follicles is one of the most important steps.
📞 For appointments and if you have questions, contact us: +998 (71) 200-03-00
📨 Source: Telegram: @eko_iksi_clinic
