Women are born with roughly 1 to 2 million eggs. That number is actually down from a peak of 6 to 7 million, reached when the fetus is about seven months along in the womb. From birth onward, the supply only declines, dropping to around 300,000 by puberty and continuing to fall until menopause.
Egg Count From Fetus to Birth
A female fetus begins developing egg cells early in pregnancy, and the count climbs rapidly. By seven months of gestational age, the ovaries hold their lifetime maximum of roughly 6 to 7 million immature eggs. Then a massive wave of natural cell death kicks in while the baby is still in the womb. By the time a girl is born, somewhere between 1 and 2 million eggs remain. That means millions are already gone before she takes her first breath.
This loss isn’t a sign that something went wrong. It’s a normal, tightly regulated process called apoptosis, or programmed cell death. The body selectively eliminates the vast majority of its egg-containing follicles throughout life, and the process starts before birth.
How the Numbers Drop Through Life
The decline continues through childhood. By the time a girl reaches puberty, about 300,000 eggs remain. From there, the loss accelerates. During a woman’s roughly 40-year reproductive lifespan, only about 400 to 500 eggs will ever be released through ovulation. That accounts for less than 0.01% of the original supply. The rest are lost to atresia, the same process of programmed cell death that began in the womb.
Each menstrual cycle, multiple follicles begin to mature, but typically only one “wins” and releases an egg. The rest of the group that started developing alongside it simply break down and are reabsorbed by the body. This means that every month, you lose far more eggs than the single one you ovulate.
By age 38, roughly 25,000 eggs remain. The pace of loss then steepens further, and by the average age of menopause (around 51), only about 750 follicles are left in the ovaries. That near-total depletion is what triggers menopause.
Can Women Make New Eggs?
For decades, the accepted science has been straightforward: women are born with all the eggs they will ever have, and the body cannot produce new ones. A 2004 study challenged this idea by reporting stem cells in mouse ovaries that appeared capable of generating fresh eggs. The finding sparked years of heated debate and follow-up research.
As of now, no one has produced definitive proof that these stem cells exist in humans or that they function under normal conditions. The initial claims relied on identifying cells using a specific protein marker thought to be exclusive to egg cells, but that marker has since been found at low levels in other tissues like the brain and kidney. So the traditional view still holds: the egg supply is fixed at birth and cannot be replenished.
What Speeds Up Egg Loss
Genetics plays the biggest role in determining how quickly your egg reserve declines and when you’ll reach menopause. But certain environmental factors can accelerate the process. Smoking is the most well-documented one. Active smokers in their late reproductive years have AMH levels (a hormone that reflects remaining egg supply) that are 44% lower than women with no smoke exposure. Animal research shows that chemicals in cigarette smoke, particularly polycyclic aromatic hydrocarbons, directly destroy egg cells.
Interestingly, former smokers don’t show the same reduction, which suggests that quitting may stop the additional damage. Passive (secondhand) smoke exposure also showed no measurable effect on egg reserve, nor did prenatal exposure to a parent’s smoking.
Other factors linked to faster depletion include certain autoimmune conditions, ovarian surgery, and chemotherapy or radiation treatment targeting the pelvic area. These can sometimes cause a dramatic, sudden drop in egg count rather than the gradual decline most women experience.
How Egg Reserve Is Measured
You can’t count your remaining eggs directly, but a blood test measuring anti-Müllerian hormone (AMH) gives a reliable estimate of your ovarian reserve. AMH is produced by the small follicles in your ovaries, so higher levels generally mean more eggs remain. An average AMH level falls between 1.0 and 3.0 ng/mL, levels below 1.0 are considered low, and levels at or below 0.4 are severely low.
To give a sense of how AMH shifts with age, here are approximate lower-range values by decade:
- Age 25: 3.0 ng/mL
- Age 30: 2.5 ng/mL
- Age 35: 1.5 ng/mL
- Age 40: 1.0 ng/mL
- Age 45: 0.5 ng/mL
These numbers represent the lower side of the expected spectrum for each age, so many women will test higher. AMH testing is commonly used in fertility evaluations and can help predict how your ovaries might respond to treatments like egg freezing or IVF. It doesn’t tell you whether you can get pregnant on your own, though. Egg quality, which declines with age independently of quantity, matters just as much.
Egg Count vs. Egg Quality
Quantity gets most of the attention, but quality is what determines whether an egg can develop into a healthy pregnancy. As eggs age, they become more prone to errors during cell division, leading to chromosomal abnormalities. This is why the risk of miscarriage and conditions like Down syndrome rises with maternal age, even in women who still have a reasonable number of eggs left.
A 38-year-old with 25,000 remaining eggs isn’t in the same position as a 25-year-old with 25,000 eggs. The younger woman’s eggs are statistically more likely to divide correctly and result in a viable pregnancy. This distinction is why fertility specialists look at both AMH levels and age when counseling patients, rather than treating egg count as the whole picture.