How many follicles should I have? Understanding follicular development

Are you going through the process of fertility testing or fertility treatments and wondering how many follicles you should have? Understanding follicular development is key to understanding your fertility, and this article will help you gain a deeper knowledge of the topic. So, let’s dive in!

The Basics of Follicular Development

The follicular phase of the menstrual cycle is the first half, during which time an egg follicle(s) begin to mature in preparation for ovulation. Follicles are fluid-filled sacs that contain an immature egg. As they grow, they produce estrogen to help thicken the lining of the uterus.

The timing, quality, and quantity of follicles are important in fertility testing, diagnosis, and treatment. Usually, only one follicle will become dominant and release a mature egg. However, under certain circumstances, more than one follicle may become dominant, which can lead to multiple eggs being released, increasing the chances of conception.

Stages of follicular development

Follicular development is a complex process that can be classified into four different stages.

Stage 1: Primordial follicles

The primordial follicles are immature ovarian follicles containing no more than an oocyte or an immature egg. Every woman is born with a finite number of primordial follicles, and the number declines with age, with fewer primordial follicles in older women.

Stage 2: Preantral follicles

Preantral follicles are small, immature follicles that develop from primordial follicles. During this stage, the follicle begins to grow and acquire a fluid-filled cavity or antrum. The antrum is the space within the follicle where the egg will mature.

Stage 3: Antral follicles

Antral follicles are follicles that have developed to a certain size and contain an antrum. They can be visualized on ultrasound, and their number and size can give an indication of ovarian reserve.

Stage 4: Mature follicles

The mature follicle is typically the largest and most dominant follicle in the ovary, containing a mature egg ready for ovulation. It measures around 18-24 mm in diameter, and its size can be monitored by ultrasound.

How Many Follicles Should I Have?

The number of follicles a woman has can vary greatly depending on a number of factors, including age, ovarian reserve, and fertility treatments.

Age and Follicle Count

A woman’s age is a significant factor in follicle count. Women are born with an average of approximately 1-2 million primordial follicles, and this number decreases continuously with age. By puberty, she has around 300,000-500,000 follicles. By age 37, the average woman has approximately 25,000 remaining follicles, and by the age of 52, most women have none left.

As women age and approach menopause, the number and quality of the follicles decrease. This results in a reduced number of follicles that are available for ovulation, which can decrease the chances of becoming pregnant.

Assessing Ovarian Reserve

Ovarian reserve refers to the quantity and quality of a woman’s remaining eggs. Ovarian reserve testing can be done via ultrasound, blood tests, or a combination of the two. It’s important to note that these tests only provide an estimate of ovarian reserve, and there is no perfect test that can accurately predict a woman’s reproductive potential.

Antral Follicle Counts

Antral follicle counts are obtained through a transvaginal ultrasound and are a direct measure of the number of follicles present in the ovary. This count is usually performed on days 2-5 of a menstrual cycle. A low antral follicle count may indicate lower ovarian reserve, while a high count could be an indicator of polycystic ovary syndrome (PCOS).

Day 3 FSH and Estradiol

On day 3 of the menstrual cycle (the third day of the period), the levels of follicle-stimulating hormone (FSH) and estradiol (E2) are measured. FSH helps stimulate the follicles to grow, while estradiol produced by the follicles helps to maintain the health of the uterus. Elevated levels of FSH or low levels of estradiol could indicate a decrease in ovarian reserve.

Anti-Mullerian Hormone (AMH)

AMH is produced by small growing follicles and can be measured at any point during the menstrual cycle. It gives a good indication of the size of the ovarian reserve. A low level of AMH may indicate a reduced number of growing follicles, which can make fertility harder to achieve.

Follicle Count in Fertility Treatments

Fertility treatments, including IVF and ovarian stimulation (OS), aim to stimulate the growth and maturation of multiple follicles simultaneously. The number of follicles that are stimulated varies depending on the individual and the treatment plan.

Ovarian Stimulation

Ovarian stimulation is a treatment used to induce ovulation, regulate menstrual cycles, and increase the chances of natural conception. It involves the use of fertility drugs, such as clomiphene citrate or gonadotropins, to stimulate the ovaries to produce multiple follicles. Depending on the individual’s response to treatment, the number of follicles produced can range from 1-2 to as many as 20-30.


In-vitro fertilization (IVF) is a technique used to achieve pregnancy in women with infertility. The process involves using drugs to stimulate the ovaries to produce multiple follicles, retrieving the mature eggs, fertilizing them in the laboratory, and then transferring the fertilized eggs (embryos) to the uterus.

The number of follicles produced typically depends on the individual’s age, ovarian reserve, and response to fertility medications. Usually, IVF aims to retrieve 8-15 mature eggs, although this number can be higher or lower, depending on the individual’s response to stimulation.

How Does Follicular Development Affect Fertility?

The quality and quantity of follicles are key factors in natural and assisted conception. Age and ovarian reserve directly affect the number and quality of the follicles, which, in turn, impacts fertility.

Natural Conception

In natural conception, follicular development plays a crucial role. As previously mentioned, only one follicle will typically come dominant and release a mature egg for fertilization. However, there may be more than one follicle in the process of development, allowing for the possibility of multiple eggs being released, which increases the chance of conception.

Fertility Treatments

In assisted reproductive technologies, such as IVF, follicular development is closely monitored to ensure optimal results. The number and size of follicles in response to treatment are used to guide the timing of the ovulation trigger, which marks the time for egg retrieval.


Understanding follicular development is essential to fertility treatments and understanding your fertility. The number and quality of the follicles are key factors in fertility testing, diagnosis, and treatment. Age, ovarian reserve, and fertility treatments can affect the number of follicles a woman will produce. By understanding follicular development, women can increase their chances of becoming pregnant through natural or treated conception.


  • Q: How many follicles are required for pregnancy?
  • A: Normally, only one mature follicle is required for pregnancy, but having multiple follicles can increase the chance of conception.
  • Q: What does a low follicle count mean?
  • A: A low follicle count could indicate reduced ovarian reserve, which may make fertility challenging to achieve.
  • Q: How can I increase the number of follicles?
  • A: A healthy lifestyle, including exercise, a balanced diet, and reducing stress, can support fertility. Fertility treatments, such as ovarian stimulation and IVF, can increase the number of follicles for conception but should only be undertaken after consultation with a fertility specialist.


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  • SF Lobo. (2000). Ovarian pathophysiology. Clin Obstet Gynecol, 43(4): 920. 10.1097/00003081-200012000-00014.
  • Tarlatzis, B. C., & Grimbizis, G. F. (2003). Correlative assessments of ovarian reserve. Journal of assisted reproduction and genetics, 20(5), 177-184.
  • Rosen, M. P., Shen, S., Hill, M. J., Chung, K., & Cedars, M. I. (2007). What is the best predictor of poor ovarian response among women undergoing IVF? Fertility and sterility, 87(1), 124-125.

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