Antral Follicle Count: How Many Follicles Is Good for IVF?
When preparing for IVF, a common concern is understanding ovarian reserve, or, in simpler terms, how many eggs remain and how well the ovaries are likely to respond to stimulation. One of the most useful tools to measure this is the antral follicle count (AFC).
That’s why so many patients ask: “How many follicles is good for IVF?”
What Is an Antral Follicle?
Women are born with all the eggs they will ever have. Over time, that supply naturally declines until menopause.
An antral follicle is a small fluid-filled follicle, typically 2–9 mm in diameter, that can be seen on ultrasound. These are sometimes called resting follicles because they represent the group of follicles just beginning to grow for that month.
Each visible antral follicle represents one egg that could potentially mature with the help of fertility medications.
The number visible on ultrasound is strongly associated with the total number of remaining microscopic follicles, which contain eggs that could develop in future cycles.
What Is an Antral Follicle Count Ultrasound?
An antral follicle count ultrasound is a short, transvaginal ultrasound performed at the beginning of the menstrual cycle, usually cycle day 2, 3, or 4.
At this point, follicles have not yet been stimulated by natural hormones, making the count more accurate.
During the ultrasound, your provider:
Examines each ovary
Counts visible 2–9 mm follicles
Estimates overall ovarian reserve and expected response to medication
Because AFC doesn’t change dramatically from month to month, this test offers a reliable picture of ovarian function and IVF prognosis.
Why Does AFC Matter for IVF?
A higher antral follicle count usually means:
Better response to stimulation medication
More follicles growing to maturity
Higher chances of success in IVF
A lower antral follicle count often indicates:
Reduced response to medication
Lower egg yield
Higher chance of cycle cancellation
Lower overall pregnancy rates, especially after age 35
For many patients, AFC is one of the strongest predictors of how the ovaries will respond to injectable stimulation medications used in IVF.
However, AFC is not perfect. Ultrasound interpretation can vary slightly among clinicians, and IVF success depends on many factors beyond follicle count, including age, egg quality, sperm quality, embryo development, and uterine health.
Normal Antral Follicle Count by Age
AFC naturally declines as ovarian reserve decreases with age. Multiple nomogram studies in diverse populations demonstrate that the antral follicle count declines by approximately 0.4–0.8 follicles per year with increasing age. Exact numbers vary, but typical ranges look like this :
| Age Range | Normal Antral Follicle Count (Approx.) |
|---|---|
| 18–25 | 15–30 follicles |
| 26–30 | 12–25 follicles |
| 31–35 | 10–20 follicles |
| 36–40 | 6–14 follicles |
| 41–45 | 4–10 follicles |
| 45+ | Often below 4 |
Women with polycystic-appearing ovaries may have very high antral follicle counts, sometimes well over 30, and often respond strongly to even low doses of stimulation medication.
Women with very low AFC may respond weakly, even with high doses of medication, and may produce only one or two mature follicles.
How Many Follicles Is Good for IVF?
There is no universal “perfect” number, but AFC ranges can offer useful guidance:
| Total AFC | What It May Suggest |
|---|---|
| Under 4 | Very low count. Higher risk of cancellation and very limited response to stimulation. |
| 4–9 | Low count. Response may be weak and may require higher doses of medication. Lower than average pregnancy rates. |
| 9–13 | Mildly reduced count. Response may be average or slightly lower. |
| 14–21 | Normal range. Most patients respond well, with a good number of mature follicles. |
| 22–35 | High count. Often strong responders, typically needing lower doses of medication. |
| 35+ | Very high count, often seen in PCOS. Higher risk for overstimulation without careful monitoring. |
These ranges are estimates, not rules. Some patients with low counts still conceive, and some with high counts may produce many eggs but still require thoughtful monitoring to avoid ovarian hyperstimulation.
The most important point: egg quantity and egg quality are not the same.
While AFC reflects the number of potential eggs, age remains the strongest predictor of genetic normality and embryo health.
What If My AFC Is Low?
A low antral follicle count doesn’t automatically mean IVF won’t work. Many patients with low AFC still respond to medication and develop mature eggs. However, low AFC may:
Require higher medication doses
Increase the chances of cycle cancellation
Reduce the number of eggs retrieved
Lower the overall probability of pregnancy
In some situations, fertility specialists may discuss modified protocols, mild stimulation, or (depending on age and goals) donor egg IVF.
AFC, Hormone Testing, and IVF Planning
Most clinics don’t rely on AFC alone. It is commonly paired with:
Day-3 FSH
Estradiol
Clinical history and age
Together, these help create the most accurate prognosis and allow your provider to tailor the safest, most effective IVF medication plan.
If you’re interested in learning more about female fertility testing or anything else about what a fertility journey can mean for you, schedule a consultation with our team today!
Key Takeaways
Antral follicle count ultrasound is one of the most accurate ways to measure ovarian reserve.
Normal antral follicle count by age declines gradually, especially after 35.
How many follicles is good for IVF? Most women fall somewhere between 5–20, but there is no single “right” number.
A very low AFC may mean a weaker response to stimulation, while a very high AFC requires careful monitoring to avoid overstimulation.
AFC is most helpful when evaluated in conjunction with AMH, FSH, age, medical history, and overall fertility goals.
Antral Follicle Count FAQ
Can an antral follicle count improve?
AFC usually reflects the underlying ovarian reserve, which naturally declines with age. Because of that, AFC doesn’t typically increase in a long-term or permanent way.
However, short-term variations can happen from cycle to cycle, and some patients see slightly higher counts after lifestyle changes, treatment for hormone imbalances, or when inflammation or cysts have been remedied. But for most women, AFC remains relatively stable and is determined mainly by age and genetics.
Does AFC predict egg quality?
Not directly. AFC tells us how many follicles are likely to respond to stimulation, but it doesn’t measure the genetic health or maturity of the eggs. Age is still the strongest predictor of egg quality.
For example, a 42-year-old with 20 antral follicles may produce many eggs, but those eggs are more likely to have age-related chromosomal abnormalities than those from a younger patient.
Is antral follicle count more accurate than AMH or FSH?
AFC and AMH are widely considered the best modern measures of ovarian reserve. Both can be strong predictors for IVF response.
FSH and estradiol are still used, but they can fluctuate more from cycle to cycle. Fertility specialists often use AFC + AMH + age together to get the clearest picture.
What is a good antral follicle count for IVF at age 35?
There is no perfect number, but many women in their mid-30s have around 8–15 antral follicles.
Some will have more, while others will have less. Even women with lower counts may still respond well to medication. The number of eggs retrieved is only part of the equation; fertilization, embryo development, and embryo genetics all play major roles in determining success.
What is a good antral follicle count at age 40?
By age 40, it’s common for AFC to be lower, often in the 4–10 range.
Some women will have higher numbers, and others will have fewer. IVF success at this age depends more heavily on egg quality than egg quantity, which is why many clinics discuss options like mild-stimulation IVF, embryo genetic testing (PGT-A), or donor eggs, depending on individual goals.
How many follicles do you need for IVF to work?
There is no strict cutoff, but many clinics prefer to see at least 3 mature follicles growing before proceeding to retrieval. That said, successful pregnancies have been achieved with even a small number of eggs.
A higher number of eggs increases the chances of creating healthy embryos, but quality matters more than quantity.
Does a high antral follicle count always mean better IVF results?
Not always. Very high AFC, especially counts above 30, can be associated with PCOS and a higher sensitivity to stimulation medications.
These patients often respond very well, but they also require careful monitoring to avoid ovarian hyperstimulation syndrome (OHSS). With proper medication adjustment and a trigger shot designed to reduce risk, many patients still have excellent outcomes.
Can AFC be wrong?
AFC is considered one of the most accurate ovarian reserve tests, but it’s not perfect.
Ultrasound interpretation can vary slightly between clinicians; ovarian cysts can obscure follicles, and the timing of the scan matters. This is why most providers repeat AFCs when needed and always interpret results alongside AMH, FSH, age, and treatment history.
