Ovarian reserve refers to the number of eggs remaining in your ovaries at any given point in time. You’re born with all the eggs you’ll ever have, roughly 1 to 2 million at birth, and that number declines steadily throughout life. By puberty, about 300,000 to 500,000 remain. By age 37, that number drops to around 25,000, and by the average age of menopause (51), only about 1,000 are left. Ovarian reserve is one of the key factors that determines fertility potential, and it can be estimated through blood tests and ultrasound.
How Ovarian Reserve Declines With Age
The loss of eggs begins before you’re even born. Egg numbers actually peak at about 6 to 7 million around 20 weeks of fetal development, then start dropping immediately. This process, called atresia, is the body naturally reabsorbing follicles that won’t be used. It never stops.
The pace of decline isn’t steady, though. From puberty through your early 30s, the drop is relatively gradual. Around age 32, the rate picks up. At 37, it accelerates again, more sharply this time. This is why fertility specialists often reference the mid-to-late 30s as a turning point. It’s not that fertility suddenly disappears, but the pool of available eggs is shrinking faster than it was a few years earlier.
Quantity Versus Quality
Ovarian reserve technically encompasses both the number and the quality of remaining eggs, but the two don’t always move together. Research on younger women with diminished ovarian reserve found that while they produced fewer eggs during fertility treatment, the quality of those eggs and the resulting embryos was comparable to women with normal reserve. In other words, having fewer eggs doesn’t automatically mean the eggs you do have are poor quality.
That said, lower ovarian reserve is associated with a higher chance of chromosomal abnormalities in embryos. Women in the bottom quarter of ovarian reserve had nearly double the rate of having all embryos come back chromosomally abnormal compared to those with higher reserve (19.3% versus 10.3%). Overall, diminished reserve is linked to roughly a 25% increase in the probability that any individual embryo will have chromosomal issues. So while quantity and quality are separate concepts, they do overlap, especially as age increases.
How Ovarian Reserve Is Measured
No single test gives a complete picture. Doctors typically use a combination of blood work and ultrasound to estimate where you stand.
AMH (Anti-Müllerian Hormone)
AMH is a hormone produced by the small follicles in your ovaries. It’s considered the most reliable blood marker for ovarian reserve because it stays relatively stable throughout your menstrual cycle, meaning it can be drawn on any day. General reference ranges:
- Average: 1.0 to 3.0 ng/mL
- Low: under 1.0 ng/mL
- Severely low: 0.4 ng/mL or below
These numbers shift with age. A typical AMH level at age 25 is around 3.0 ng/mL, dropping to about 2.5 at 30, 1.5 at 35, 1.0 at 40, and 0.5 at 45. During IVF, AMH below 0.5 ng/mL is associated with retrieving fewer than three eggs. When AMH is too low to detect, pregnancy through IVF is rare.
Antral Follicle Count (AFC)
This is done via transvaginal ultrasound during the early part of your menstrual cycle. The doctor counts the small follicles (2 to 10 mm in diameter) visible in both ovaries. These antral follicles represent the eggs that could potentially respond to stimulation in a given cycle. An AFC of 3 to 10 is considered low and suggests reduced chances of success with IVF.
Day 3 FSH
Follicle-stimulating hormone (FSH) is measured on day 3 of your menstrual cycle. When ovarian reserve is declining, the brain has to produce more FSH to coax the ovaries into developing an egg each month. An FSH level above 10 mIU/mL on day 3 suggests decreased reserve. Estradiol levels at or above 80 pg/mL on the same day can also signal a problem. FSH is less reliable than AMH because it can fluctuate significantly from one cycle to the next. A normal FSH result one month doesn’t rule out low reserve.
What Affects Ovarian Reserve Besides Age
Age is the biggest factor, but it’s not the only one. Ovarian reserve can be influenced by genetics, environmental exposures, medical treatments, and lifestyle factors. If your mother, sister, or other close female relative experienced premature ovarian insufficiency (when the ovaries stop functioning before age 40), you may be at higher risk yourself. The American Society for Reproductive Medicine recommends that women with a family history of this condition consider ovarian reserve testing.
Smoking is one of the most well-documented lifestyle factors. It accelerates egg loss, and interestingly, a mother’s smoking during pregnancy can even affect the ovarian reserve of her unborn daughter. The same goes for other prenatal exposures: maternal undernutrition, significant weight gain during pregnancy, and certain environmental toxins have all been linked to smaller ovarian reserves in offspring. Some of this damage happens during fetal development, when the initial pool of eggs is being formed.
Certain medical treatments directly reduce ovarian reserve. Chemotherapy and radiation therapy, particularly when directed near the pelvis, can destroy a significant portion of the egg supply. Ovarian surgery, including procedures to remove cysts or treat endometriosis, can also reduce the number of remaining follicles.
What the Numbers Mean for Fertility
Ovarian reserve testing tells you something important, but it doesn’t tell you everything. These tests are best at predicting how your ovaries will respond to fertility medications during IVF. They’re less useful for predicting whether you’ll conceive naturally.
During IVF, the numbers paint a clearer picture. AMH between 1.0 and 3.5 ng/mL predicts a normal ovarian response to stimulation medications, while levels above 3.5 suggest the ovaries might over-respond (increasing the risk of complications like ovarian hyperstimulation). Women in the bottom 10% of ovarian reserve have triple the rate of producing no usable embryos compared to those with higher reserve (17% versus 5.3%), and lower live birth rates per cycle (41.2% versus 53.1%).
A low result doesn’t mean you can’t get pregnant. It means the window may be narrower and the odds per attempt may be lower. Many women with diminished ovarian reserve do conceive, sometimes naturally and sometimes with assistance. The critical thing low results signal is urgency: if pregnancy is a goal, it’s worth acting on that information sooner rather than later, since ovarian reserve only moves in one direction.
When Testing Is Typically Done
Ovarian reserve testing isn’t part of a routine annual exam. It’s most commonly ordered when you’re being evaluated for infertility, considering egg freezing, or planning IVF. It may also be recommended if you have risk factors like a family history of early menopause, prior ovarian surgery, or exposure to treatments known to damage the ovaries.
Some women request testing proactively, even without fertility concerns, simply to understand where they stand. While the results can be informative, they come with an important caveat: a normal ovarian reserve doesn’t guarantee fertility, and a low result doesn’t guarantee infertility. These are measures of egg supply, not a fertility forecast. They work best as one piece of a larger picture that includes age, overall health, and reproductive history.