By age 30, a woman typically has around 100,000 to 150,000 eggs remaining in her ovaries. That sounds like a lot, but it represents a steep drop from the 1 to 2 million eggs present at birth and the 300,000 to 400,000 still available at puberty. Most of this loss happens silently, with no symptoms or outward signs.
Why the Number Drops So Quickly
Women don’t produce new eggs. The entire supply is set before birth, and from that point on, eggs are steadily lost through a natural process called atresia. Each month, your body recruits a batch of immature follicles (the tiny sacs that contain eggs), but only one typically matures and ovulates. The rest of that batch simply dissolves. This means you lose far more than one egg per cycle. Across your teens and twenties, hundreds of eggs disappear every month, regardless of whether you’re on birth control, pregnant, or not ovulating at all.
By the time you reach 30, roughly 90% of your lifetime egg supply is already gone. The decline continues at a steady pace through your early thirties, then accelerates noticeably after 35.
Egg Quantity vs. Egg Quality
The number of eggs you have is only part of the picture. Egg quality, meaning whether an egg has the correct number of chromosomes, matters just as much for fertility. At 30, the news on quality is still relatively good. Data from egg donor cycles shows that about 75% of eggs from women ages 26 to 30 are chromosomally normal. That’s slightly lower than the roughly 81% seen in women ages 21 to 25, but it’s a far cry from the sharp quality decline that begins in the mid-to-late thirties, when the proportion of chromosomally abnormal eggs rises steeply.
Chromosomal problems in eggs are the leading cause of miscarriage and the main reason fertility drops with age. So while a 30-year-old has fewer eggs than she did at 20, the eggs she does have are still mostly viable.
What This Means for Fertility at 30
A healthy 30-year-old has roughly a 20% chance of conceiving in any given menstrual cycle, and about an 85% chance of conceiving within a year of trying. Fertility starts its initial slow decline around this age, but for most women, 30 is still well within the window of strong reproductive potential. The more significant shift happens after 35, when both egg quantity and quality drop at a faster rate.
That said, individual variation is enormous. Some 30-year-olds have ovarian reserves closer to what’s typical for a 25-year-old, while others may already show signs of diminished reserve. Genetics, smoking, prior ovarian surgery, and certain autoimmune conditions can all push the timeline earlier.
How Doctors Measure Your Egg Supply
If you’re curious about where you personally stand, two tests give a useful snapshot. The first is an AMH blood test (anti-Müllerian hormone), which reflects the pool of immature follicles waiting in your ovaries. For a 30-year-old, a typical AMH level is around 2.5 ng/mL or higher. Lower values may suggest a smaller-than-expected reserve for your age.
The second test is an antral follicle count, done via transvaginal ultrasound. A technician counts the small, visible follicles on each ovary. Women ages 30 to 34 average about 18 antral follicles, with that number declining by roughly 1.5 per year through the early thirties. By ages 35 to 39, the average drops to around 8.
Neither test tells you whether you can or can’t get pregnant. They estimate the size of your remaining egg pool, which helps with planning, especially if you’re considering egg freezing or IVF. A woman with a lower-than-average reserve may still conceive naturally, while a woman with a high reserve could face other fertility challenges unrelated to egg count.
The Rate of Loss After 30
Between 30 and 35, the decline in egg count is steady but not dramatic. You’re losing eggs at roughly the same pace as your late twenties. The inflection point comes around 35 to 37, when the rate of loss accelerates sharply. By 40, most women have fewer than 20,000 eggs remaining, and the proportion of chromosomally normal eggs has dropped significantly.
This timeline explains why fertility specialists often describe the early thirties as a transitional period. You’re no longer at peak fertility, but you still have substantial reserves and high egg quality. The practical window for most women is wider than the anxiety around “the biological clock” might suggest, though waiting until the late thirties does meaningfully change the odds.