Follicle sizes by days of the cycle

Since they hold and release the egg during ovulation, follicles are essential to a woman’s menstrual cycle. The follicles’ changing size during the cycle indicates how the body is getting ready for ovulation.

For those who are tracking their reproductive health or trying to conceive, knowing how follicle sizes change over the course of the cycle can be useful. Follicles undergo distinct growth rates in response to hormonal fluctuations that transpire throughout the menstrual cycle.

Every woman’s follicle development is unique and may change from cycle to cycle. However, broad trends can shed light on typical behavior and aid in our understanding of how fertility functions.

Day of Cycle	Follicle Size (mm)
Day 1-4	Small, less than 4 mm
Day 5-7	Growing, around 5-8 mm
Day 8-10	9-12 mm
Day 11-14	13-18 mm
Day 15+ (Ovulation)	18-25 mm

How growth occurs?

Follicles are given to a woman by birthright. Newborn girls have from 500 thousand to a million primordial follicles in their ovaries, the size of which is negligible. With the onset of puberty, a girl begins a monthly continuous process of folliculogenesis, which will last throughout her reproductive life and will end only with the onset of menopause. A woman is given about 500 germ cells throughout her life, they will mature one by one in each menstrual cycle, and on the day of ovulation they will leave the bubble-refuge, having reached its maximum size. After ovulation, fertilization is possible within 24-36 hours. For conception, only one follicle and one egg are needed. With the onset of puberty, a girl begins to produce a hormone responsible for follicular growth. It is called FSH – follicle-stimulating hormone. It is produced by the anterior lobe of the pituitary gland. Under its influence, the primordial vesicles begin to increase, and already during the next ovulation, some of them first become preantral, and then antral, inside which there is a cavity filled with liquid.

There can be from 5 to 25 antral follicles at the very beginning of a woman"s cycle. Their number allows doctors to predict how capable a woman is of conceiving on her own, whether pregnancy is possible without stimulation and the help of doctors. The norm is considered to be from 9 to 25 bubbles. If a woman has less than 5 antral follicles, then the diagnosis of "infertility" is established, in which case IVF with donor eggs is indicated. Antral follicles grow at approximately the same rate, with the same speed, but soon a leader begins to form, growing faster than the others – such a bubble is called dominant. The rest slow down their growth and undergo reverse development. And the dominant one continues to grow, the cavity with liquid in it expands, in which the egg matures. By the middle of the cycle, the follicle reaches a large size (from 20 to 24 mm), at which it usually bursts under the influence of the hormone LH. The egg becomes available for fertilization in the next 24-36 hours.

• Menstruation
• Ovulation
• High probability of conception

In the event of a 28-day cycle, ovulation takes place on the 14th day, 14 days prior to the commencement of the menstrual cycle. Since there is frequently a deviation from the average value, the computation is imprecise.

In addition to the calendar method, you can check cervical mucus, measure basal temperature, use special tests or mini-microscopes, and test for progesterone, estrogens, LH, and FSH.

Folliculometry (ultrasound) can be used to definitively determine the day of ovulation.

1. Losos, jonathan b.; Raven, Peter H.; Johnson, George B.; Singer, Susan R. Biology. New York: McGRAW-HILL. PP. 1207-1209.
2. Campbell n. A., Reece j. B., Urry l. A. E. a. Biology. 9th ed. – Benjamin cummings, 2011. – p. 1263
3. Tkachenko b. AND., Brin c. B., Zakharov Yu. M., Neduspasov in. ABOUT., Pyatin in. F. Human physiology. Compendium / Ed. B. AND. Tkachenko. – M.: GEOTAR-Media, 2009. – 496 p.
4. https: // ru.Wikipedia.org/wiki/Овуляция

A new education, a yellow body that produces progesterone, is made up of the remnants of a former follicle. If there is no conception, the yellow body dies in 10–12 days and produces significantly less progesterone before menstruation. The yellow body continues to function through the end of the first trimester of pregnancy.

According to the same scheme, in the absence of pregnancy, a new stage of follicogologene begins on the first day of the cycle, or the first day of the subsequent menstrual cycle. Monthly ovulation happens if a woman works for another woman normally and her hormonal background is unproblematic. One or two anovolets of the cycle per year are regarded as appropriate. As women age, their genetic material ages and their follicular supply runs out, which causes the number of cycles without follicle ripening and ovulation to increase to 5–6 per year. This is normal.

Because nature has not made it possible for it to be replenished, it is crucial to keep an eye on your health and take good care of your ovulatory reserve.

Change in size

It is challenging to determine the ideal follicle size at a given point in its development. The information in the tables is only approximative and does not account for a woman’s unique characteristics. Since folliculogenesis is an ongoing process, the size of the bubbles varies with each day of the cycle.

Follicles in the early stages of the cycle are no larger than 2-4 mm. However, as they develop, fewer antral follicles are present overall, and their diameter increases. The dominant follicle is typically identifiable by the eighth day of the cycle, at which point its size is the only information measured until ovulation.

Table showing follicle sizes by day.

The cycle’s day

Follicle size

Modifications

The quantity of antral follicles can be counted.

A reduction in the quantity of antral vesicles occurs.

There is a discernible dominant follicle.

The main follicle develops

The cavity containing the oocyte can be found inside the dominant follicle.

The follicle’s interior cavity enlarges.

The follicle itself approaches the ovarian membrane as much as possible, and a tubercle forms on its surface.

A stigma is identified on the follicle’s surface.

21–22 mm (although 23–24 mm is suitable)

The follicle is primed to release eggs.

Since each case is unique, it is not necessary for the dominant vesicle to grow to a length of 11–18 mm on the 10–11 day of the cycle. Nevertheless, the size of the follicle is still used to predict the ovulation period. For instance, if a woman has a 16 mm follicle, she will be advised to wait for ovulation because the size of the vesicle does not indicate that rupture will occur anytime soon.

A cystic formation is more likely to be suspected by the doctor than a normal ovulatory cycle if the follicle has a size greater than 25 mm on the 7-9th day of the cycle or at any other time before ovulation (26-27, 30-34 mm, and so forth).

Crucial! For women who do not receive hormonal treatment, the aforementioned norms are pertinent. Ovulation stimulation may cause the sizes to vary.

How to check?

Naturally, it is not possible for you to measure the follicles. Folliculometry and a visit to a physician are the only ways to accomplish this. This kind of ultrasound examination allows for the dynamic observation of a woman’s ovarian health. The first ultrasound is typically performed as soon as the menstrual cycle ends; this allows for the best chance to determine the number of antral vesicles on days 7-8 of the cycle. After that, an ultrasound is performed frequently—every two to three days—to ensure that the day of ovulation is not missed.

Based on the average size of the follicle, an ultrasound physician can determine when it is optimal to induce ovulation, when it is appropriate to administer the IVF protocol’s ovarian puncture procedure for egg retrieval, and whether or not ovulation occurred during the current cycle.

In order to determine the type and causes of infertility as well as the wisdom of stimulation, follicle monitoring is a must.

A woman may be shocked to learn during the initial procedure that her ovaries are producing a sizable number of follicles that are maturing. For those who are antral, this is quite typical. Alarm is raised in situations where there are either too few or too many of these bubbles. The doctor will suspect polycystic ovary syndrome if there are more than 26, which makes it impossible to conceive without treatment.

Less than five antral bubbles (a single follicle, two, three, or four follicles) indicate infertility in the woman; ovarian stimulation and IVF are not used in this situation because the follicles do not grow even under stimulation. Using donor eggs in IVF is acceptable.

Eleven to twenty-five follicles are thought to be the ideal number for trouble-free conception. This is the amount that represents a typical level of fertility and follicular reserve. They discuss a decreased follicular reserve if the number is between 6 and 10, in which case the woman can receive stimulation.

Causes of folliculogenesis disorders

Hormonal levels regulate the processes involved in folliculogenesis, which are influenced by the ratios and concentrations of the hormones FSH, estradiol, luteinizing hormone, progesterone, testosterone, and prolactin. Therefore, any disruption in the endocrine accompaniment can cause a violation in the follicle maturation process, resulting in either an excessively slow or rapid maturation. In the first scenario, ovulation may occur later; in the second, it may occur earlier. Neither of them is ideal for a healthy conception.

Disorders related to folliculogenesis can be diverse. For instance, persistence prevents the follicular membrane from rupturing. Usually, low levels of the hormone LH are linked to this kind of phenomenon. In this instance, the follicle remains on the surface of the gonad for a few more weeks after the egg overripens and dies. This results in the menstrual cycle failing, making conception impossible during this time.

Ovulation is also prevented by luteinization of the follicle, which causes the corpus luteum to develop prior to the rupture. Follicle atresia is the term used to describe when a follicle abruptly stops developing because it fails to reach the necessary size. The woman is unable to conceive because the ovulation process is interfered with in every instance.

There are several causes for the disruption of follicle development. A woman can become a mother on her own without the assistance of medical professionals if certain transient factors are removed, which will restore the cycle.

There are more severe causes that call for medical intervention, the assistance of reproductive specialists, embryologists, and other experts who can bring a woman the joy of motherhood even in situations that appear hopeless.

Short-term disturbances may result in:

• excessive physical activity, professional sports;
• passion for mono-diets, sudden weight loss or weight gain in a short period of time;
• chronic stress, emotional instability, worries;
• work in an enterprise with a high level of occupational hazards (with paints, varnishes, nitrates, on the night shift, in conditions of strong vibration and increased electromagnetic radiation);
• travel and air travel, if they are associated with a change in climate and time zones;
• cancellation of oral contraceptives;
• illnesses suffered in the current month with an increase in body temperature.

Because we sometimes fail to recognize symptoms like heavier discharge or menstrual delays, women with follicular maturation disorders frequently do not detect any symptoms at all.

A number of illnesses and ailments that disrupt the endocrine background can be listed as pathological causes of follicular maturation disorders:

• pathologies of the pituitary gland, hypothalamus;
• violation of ovarian function;
• inflammatory and infectious diseases of the genital tract and pelvic organs;
• ovarian tissue injuries, consequences of surgical intervention;
• thyroid gland dysfunction, adrenal cortex dysfunction.

Hormonal disruptions are frequently preceded by bad habits, prolonged use of antibiotics, antidepressants, and anticoagulants, as well as childbirth and abortion.

Gaining knowledge about follicle sizes throughout the menstrual cycle can be extremely beneficial for improving reproductive health and fertility. Throughout the cycle, folliculles develop and alter, and each stage is crucial for ovulation and the likelihood of conception.

Families who are trying to conceive can benefit from knowing when ovulation is likely to occur by tracking follicle size. It can also help diagnose problems associated with irregular cycles or infertility, providing a more comprehensive understanding of reproductive health.

Whether follicle growth is monitored naturally or with medical assistance, it is important to do so in order to gain a better understanding of how the body functions during the cycle. By having this information, families will be better equipped to make decisions regarding reproductive health and family planning.

Throughout a woman’s menstrual cycle, the size of her follicules varies, which is important for fertility. Follicles are tiny in the early stages of the cycle, but they gradually enlarge as ovulation draws near. When a dominant follicle is ready to release an egg, it usually reaches a size of 18–24 mm in the middle of the cycle. Monitoring these sizes can increase the likelihood of conception and provide insight into ovulation.

Video on the topic

Counting antral follicles (AFC). How to correctly count antral follicles.

Size of the dominant follicle during ovulation

Ovarian reserve at 36 years old. 1-2 follicles in a section is ovarian exhaustion? Dementeva S.N.

🔎 Folliculometry

What is Folliculometry: how is ultrasound performed, on what day of the cycle. Maturity of the follicle in the ovary

On what day to do an ultrasound to find out if the follicle is maturing?

Follicle development and ovulation.

Ovulation and the corpus luteum in the ovary