By age 50, most women have roughly 1,000 eggs or fewer remaining in their ovaries. That’s a dramatic drop from the approximately 2 million they were born with, and it signals that the body is at or very near menopause. Understanding what’s happening at this stage can help clarify why fertility declines so sharply in the late 40s and what those changes mean for your body overall.
The Numbers From Birth to 50
Your egg supply peaks before you’re even born. During fetal development, the ovaries contain around 7 million immature egg cells. By birth, that number has already fallen to about 2 million. By puberty, roughly 400,000 remain. From that point forward, you lose eggs every single menstrual cycle, not just the one that gets released during ovulation, but dozens of others that begin developing and then break down naturally in a process called atresia.
This loss isn’t steady. It follows a curve that starts gradual and then steepens. The rate of egg loss roughly doubles around age 37, when the reserve drops to about 25,000 follicles. From there, the decline picks up speed over the next decade or so. By the time the count reaches around 1,000, the ovaries can no longer sustain regular hormonal cycles, and menopause begins. The average age of menopause in the United States is 52, though the transition period (perimenopause) can start five or six years earlier, when follicle counts fall into the 1,000 to a few thousand range.
So at exactly 50, where you fall depends on your individual biology. Some women still have a small reserve supporting irregular cycles. Others have already crossed the menopause threshold. But the ballpark figure of around 1,000 eggs is what researchers consistently find for women in this age window.
Why Egg Loss Speeds Up Before Menopause
The acceleration isn’t random. Research points to changes at the cellular level that make the ovaries less efficient at keeping dormant eggs in reserve. Normally, the vast majority of your eggs sit in a resting state, waiting for a hormonal signal to begin developing. As you age, the molecular brakes that keep those resting eggs dormant start to weaken. More eggs get activated than necessary, and most of them die off before reaching maturity.
At the same time, the support cells surrounding each egg become more prone to dying off through programmed cell death. This is driven by shifts in specific protective proteins that decline with age. The result is a double hit: eggs leave the resting pool faster, and more of them fail during development. This is why the decade between your late 30s and late 40s accounts for such a large proportion of total egg loss.
Egg Quality Matters More Than Count
The number of eggs remaining is only part of the picture. The eggs that survive to age 50 are significantly more likely to carry chromosomal abnormalities than eggs from a younger woman. When an egg has the wrong number of chromosomes, it either can’t be fertilized, fails to implant, or results in a miscarriage.
Data from genetic testing of embryos in fertility clinics shows just how steep this quality decline is. Among women in their early 20s, about 75% of eggs are chromosomally normal. By the mid-to-late 40s, that number drops to essentially zero. In one large analysis of nearly 6,000 embryo biopsies, women aged 47 to 48 had a 0% rate of chromosomally normal embryos. This means that even if a woman at 50 still has eggs and is still ovulating, the chance of any individual egg being viable for a healthy pregnancy is extremely low.
The miscarriage rate reflects this reality. For women under 30, about 10% of pregnancies end in miscarriage. For women over 45, that figure climbs above 50%.
What This Means for Fertility at 50
Natural pregnancy at 50 is not impossible, but it is exceptionally rare. Fertility declines in two phases: a slow, steady drop between ages 20 and 35, followed by a much sharper decline over the next 10 years. By 45, very few women conceive naturally. In one study of spontaneous pregnancies in women over 45, the average age at the final delivery was about 45.7 years, with the oldest being 49.
The combination of a nearly depleted egg supply, extremely high rates of chromosomal abnormality, and elevated miscarriage risk makes unassisted conception at 50 a statistical outlier. Women who do become pregnant in their late 40s and early 50s through fertility treatment are typically using donor eggs from younger women, which sidesteps both the quantity and quality problems.
How to Gauge Your Own Reserve
If you’re approaching 50 and wondering where you stand, two blood tests can give some insight. Anti-Müllerian hormone (AMH) is produced by the small follicles in your ovaries, and its level correlates with how many eggs you have left. Lower AMH suggests a smaller reserve. This test is considered one of the earliest markers of the approach toward menopause, though it’s not yet standard practice for that purpose.
Follicle-stimulating hormone (FSH) works differently. Your brain produces more FSH when the ovaries aren’t responding well, essentially shouting louder to get a weaker organ to work. An FSH level above 30 mIU/mL, combined with at least a year without a period, is the standard marker for menopause. If your FSH is elevated but you’re still having occasional periods, you’re likely in perimenopause, with a reserve that’s winding down but not yet fully depleted.
Neither test tells you the exact number of eggs you have. But together, they paint a reliable picture of whether your ovaries are still functionally active or have crossed into post-reproductive territory. For most women at 50, these markers confirm what the biology predicts: the ovarian reserve is at or near its endpoint.