A healthy 30-year-old has roughly a 20% chance of conceiving per cycle. By 35, it's about 15%. By 40, approximately 5%. The decline is driven primarily by egg quality (increasing chromosomal errors), not egg quantity. But the numbers are population averages — individual variation is enormous. AMH and antral follicle count can tell you where you stand relative to your age, but nothing predicts egg quality except trying.
The Numbers
Egg Count Over a Lifetime
| Age | Approximate Eggs Remaining | Context |
|---|---|---|
| Birth | ~1–2 million | Peak lifetime supply. You never make new eggs. |
| Puberty | ~300,000–400,000 | Most eggs have already died via atresia (natural cell death). |
| 25 | ~200,000 | Fertility is near peak. ~400 eggs will actually ovulate in a lifetime. |
| 30 | ~100,000–150,000 | Decline accelerating but not yet critical for most women. |
| 35 | ~50,000–80,000 | Rate of decline steepens. Quality decline begins outpacing quantity. |
| 37–38 | ~25,000–50,000 | Inflection point: decline in both quantity and quality accelerates sharply. |
| 40 | ~10,000–25,000 | Significant quality decline. ~40–60% of eggs are chromosomally abnormal. |
| 45 | ~1,000–5,000 | Natural conception rate <1% per cycle. >90% of eggs chromosomally abnormal. |
Data from Wallace & Kelsey (2010), PLOS ONE. Numbers are median estimates with wide individual variation.
Per-Cycle Conception Probability
| Age | Chance Per Optimally-Timed Cycle | Cumulative After 6 Months | Cumulative After 12 Months |
|---|---|---|---|
| 25 | 25–30% | ~80% | ~93% |
| 30 | 20–25% | ~75% | ~90% |
| 35 | 15–20% | ~60–70% | ~80–85% |
| 38 | 10–15% | ~50–55% | ~70–75% |
| 40 | 5–10% | ~30–40% | ~50–60% |
| 43 | 2–5% | ~15–25% | ~25–40% |
Per-cycle rates based on Dunson et al. (2004). Cumulative calculations assume consistent, well-timed intercourse each cycle.
What's Really Declining: Quality, Not Just Quantity
The conversation around “running out of eggs” is misleading. Women at 35 still have tens of thousands of eggs — far more than they could ever use. The real issue is that the proportion of eggs with chromosomal abnormalities (aneuploidy) increases dramatically with age:
| Age | Estimated Aneuploidy Rate (% of Eggs) | Implication |
|---|---|---|
| Under 30 | 20–30% | Most eggs are chromosomally normal |
| 30–34 | 30–40% | Still majority normal |
| 35–37 | 40–50% | Approaching even odds |
| 38–40 | 50–70% | Majority of eggs now aneuploid |
| 41–42 | 70–80% | Finding a normal egg becomes difficult |
| 43+ | 80–90%+ | IVF with own eggs has very low success rates |
Based on PGT-A data from large IVF cohorts (Franasiak et al., 2014).
Aneuploidy (wrong number of chromosomes) is the primary cause of early miscarriage and failed implantation. A chromosomally abnormal embryo usually either fails to implant, miscarries in the first trimester, or (rarely) leads to conditions like Down syndrome (trisomy 21). This is why miscarriage rates increase with age: not because the uterus is failing, but because the embryos are more likely to be genetically abnormal.
The 37–38 inflection point
Reproductive endocrinologists consider 37–38 a critical inflection point because both the rate of egg loss and the rate of aneuploidy increase sharply. This doesn't mean 37 is “too late” — the majority of 37-year-olds can still conceive. But it does mean that the window for intervention (egg freezing, beginning treatment) narrows meaningfully after this age. If you're 35+ and considering children in the future, getting an AMH test and antral follicle count now gives you data to plan with.
AMH: Your Ovarian Reserve Marker
Anti-Müllerian Hormone (AMH) is a blood test that estimates your remaining egg supply (ovarian reserve). It can be drawn on any day of your cycle and gives a snapshot of where you fall relative to your age.
| AMH Level (ng/mL) | Interpretation | Context |
|---|---|---|
| Over 3.0 | High reserve | Reassuring; also associated with PCOS if very high (>5.0) |
| 1.5–3.0 | Normal reserve | Expected range for women under 35 |
| 1.0–1.5 | Slightly diminished | May be normal for 35–40; worth monitoring |
| 0.5–1.0 | Diminished reserve | Reduced response to IVF stimulation; earlier intervention advisable |
| Under 0.5 | Significantly diminished | Limited eggs remaining; IVF may still work but with lower yields |
What AMH does NOT tell you
AMH measures quantity, not quality. A 38-year-old with an AMH of 3.0 still has age-appropriate egg quality issues (higher aneuploidy rates) despite having plenty of eggs. Conversely, a 28-year-old with an AMH of 0.8 may have fewer eggs but they're likely to be mostly chromosomally normal. AMH tells you how much time you have and how well you'd respond to IVF stimulation — it does not predict your ability to conceive naturally.
IVF Success Rates by Age
IVF success rates provide the clearest picture of how age affects fertility, because the technology controls for timing and sperm delivery — isolating egg quality as the primary variable.
| Age at Retrieval | Live Birth Rate Per Transfer (Own Eggs) | Live Birth Rate (Donor Eggs) |
|---|---|---|
| Under 35 | 45–55% | 50–55% |
| 35–37 | 35–45% | 50–55% |
| 38–40 | 22–30% | 50–55% |
| 41–42 | 12–18% | 50–55% |
| 43+ | 3–8% | 50–55% |
Data from 2022 CDC/SART national summary. Note that donor egg rates are consistently high because donors are typically 21–29.
The donor egg column is revealing: when you use eggs from a young donor, success rates are high regardless of the recipient's age. This proves that it's the egg's age that matters, not the uterus's. A 45-year-old uterus can carry a pregnancy just as well as a 30-year-old's — the limiting factor is egg quality.
Consider Your Options
If age is a factor, egg freezing or IVF abroad can preserve your options at a fraction of US costs.
Explore IVF in Colombia