A woman at age 35 has roughly 25,000 eggs remaining. That number comes from population averages, and individual counts can vary widely, but it represents a significant drop from the approximately 2 million eggs present at birth and the 400,000 still available at puberty. Understanding what this number means for fertility requires looking beyond the count itself, because egg quality matters just as much as quantity.
How Egg Count Changes Over a Lifetime
Women are born with all the eggs they will ever have. There’s no way to produce new ones. From birth onward, the supply steadily shrinks through a natural process of cell death that happens regardless of pregnancy, birth control use, or anything else. By adolescence, roughly 400,000 eggs remain. By age 37, that number drops to about 25,000. By menopause, around age 51, only about 1,000 immature eggs are left, and none of them are capable of producing a pregnancy.
The math might seem alarming at first. Losing nearly 375,000 eggs between puberty and your mid-thirties sounds dramatic. But keep in mind that during each menstrual cycle, a whole group of eggs begins maturing and most are reabsorbed by the body. Only one (occasionally two) gets released during ovulation. Over a reproductive lifetime, a woman ovulates roughly 400 to 500 eggs total. The vast majority of eggs are lost through this background process, not through ovulation itself.
Why 35 Is a Turning Point
Age 35 gets so much attention because the decline in fertility accelerates around this time. Fertility starts declining gradually at about age 32, then drops more rapidly after 37. That acceleration is why medical guidelines recommend a faster workup for women over 35 who haven’t conceived after six months of trying, compared to the standard 12-month timeline for younger women.
The shift isn’t just about having fewer eggs. It’s about the proportion of eggs that are chromosomally normal. In women aged 31 to 35, about 39% of embryos tested in one large study were chromosomally abnormal. For women in their early twenties, that rate was closer to 28%. By 40, the abnormality rate climbs much higher. Chromosomal problems in eggs are the primary reason miscarriage rates increase and pregnancy rates decrease with age.
Egg Quality vs. Egg Quantity
Having 25,000 eggs at 35 is still far more than you’d ever need for pregnancy. The real issue is what percentage of those eggs are healthy enough to result in a viable pregnancy. Each egg carries a copy of your chromosomes, and as eggs age, errors during cell division become more common. These errors lead to embryos with the wrong number of chromosomes, which either fail to implant, miscarry early, or in rare cases result in genetic conditions.
This is why two women who are 35 with similar egg counts can have very different fertility experiences. One may conceive quickly with no issues, while another may struggle. The egg count tells you about your ovarian reserve (how many eggs you have left to work with) but says little about how many of those eggs are chromosomally normal.
Monthly Pregnancy Odds at 35
For healthy couples in their twenties and early thirties, the chance of conceiving in any given menstrual cycle is about 25%, or one in four. That number decreases through the mid-thirties, though no single widely cited figure exists for exactly age 35. By 40, it drops to about one in ten per cycle. Most women at 35 fall somewhere between those two benchmarks, with the decline accelerating as they approach 37 and beyond.
These are per-cycle odds, so they compound over time. A 15 to 20% chance per month still adds up to a strong cumulative probability over six months to a year of trying. The concern at 35 isn’t that pregnancy is unlikely in any absolute sense. It’s that the window is narrowing, and conditions that impair fertility (endometriosis, fibroids, diminished ovarian reserve) become more common with age, potentially compounding the natural decline.
How to Check Your Own Egg Supply
Population averages are useful context, but they can’t tell you where you personally stand. Two tests give a clearer picture of your individual ovarian reserve.
The first is an AMH blood test, which measures a hormone produced by the small follicles in your ovaries. Higher levels suggest a larger remaining egg supply. At age 35, a level around 1.5 ng/mL is on the lower end of the expected range. Values above that suggest a more robust reserve, while significantly lower values may indicate a smaller-than-average egg supply for your age. AMH can be tested on any day of your cycle with a simple blood draw.
The second is an antral follicle count, done via transvaginal ultrasound early in your menstrual cycle. A technician counts the small, resting follicles visible on each ovary. In a study of women averaging about 35 years old, the mean count was roughly 16 follicles, though individual counts ranged from 1 to 58. The count tends to decline by about one follicle per year in the mid-thirties.
Neither test measures egg quality directly. They estimate quantity. But quantity and quality tend to track together with age, so these results combined with your age give fertility specialists a reasonable picture of where you stand. If you’re 35 and considering pregnancy in the next few years, these tests can help you and your doctor make more informed decisions about timing or whether to explore options like egg freezing.