Fertility by Age Calculator

Q: What is the monthly fertility rate by age?

Based on published research and ACOG estimates: age 20–24 ≈ 25–28% per cycle; age 25–29 ≈ 22–25%; age 30–32 ≈ 20%; age 33–34 ≈ 18%; age 35–37 ≈ 14–15%; age 38–39 ≈ 10%; age 40–42 ≈ 6%; age 43–44 ≈ 4%; age 45–47 ≈ 2%; age 48+ ≈ 1%. These are population averages — individual rates vary based on ovarian reserve, health, and partner factors.

Q: What is the probability of getting pregnant within 12 months by age?

Using the geometric formula P = 1 − (1 − monthly rate)^12: age 25 ≈ 97%; age 30 ≈ 93%; age 35 ≈ 85%; age 38 ≈ 72%; age 40 ≈ 72%; age 42 ≈ 52%; age 45 ≈ 21%. These are estimates for the average woman at each age with no known fertility issues. Actual rates vary by individual. Note that 'trying for 12 months' is the threshold for seeking evaluation only for women under 35.

Q: At what age does female fertility start to decline?

Fertility begins declining gradually in the late 20s, more noticeably in the early 30s, and significantly after age 35. The decline accelerates further after 37–38. At 35, the ACOG notes a 'substantial decrease in fertility' and recommends earlier evaluation (after 6 months). The most dramatic decline occurs between 40 and 45. However, 'decline' describes population averages — individual women vary substantially, and some women in their early 40s have better ovarian reserves than women in their mid-30s.

Q: What is the Down syndrome risk by maternal age?

Down syndrome (Trisomy 21) risk per pregnancy increases sharply with maternal age: age 25 ≈ 1 in 1,250; age 30 ≈ 1 in 940; age 35 ≈ 1 in 350; age 38 ≈ 1 in 179; age 40 ≈ 1 in 100; age 42 ≈ 1 in 68; age 45 ≈ 1 in 30. Prenatal screening (NIPT, nuchal translucency ultrasound, quad screen) can detect Down syndrome and other chromosomal conditions early in pregnancy. ACOG recommends offering screening to all pregnant women regardless of age.

Q: When should I see a fertility specialist?

ACOG guidelines: under 35 — seek evaluation after 12 months of regular unprotected intercourse without conception; age 35–37 — seek evaluation after 6 months; age 38 or older — seek evaluation after 3 months. Earlier evaluation is appropriate for anyone with known risk factors: irregular periods, prior pelvic infections, endometriosis, prior ectopic pregnancy, recurrent miscarriage, or a partner with known male factor infertility. Earlier referral is never wrong.

Q: Does the father's age affect fertility?

Yes. Male fertility declines with age, though less dramatically than female fertility. Sperm count, motility, and morphology decline gradually from the late 30s. More significantly, sperm DNA fragmentation increases with age, which raises miscarriage risk and (less conclusively) risk of certain conditions in offspring. ACOG considers paternal age above 40 a mild risk factor. Male factor infertility (regardless of age) accounts for approximately 40–50% of all infertility cases and should be evaluated early with a semen analysis.

Q: How does IVF success rate vary by age?

IVF success rate (live birth per transfer) declines sharply with maternal age when using the woman's own eggs: age 35 ≈ 40%; age 38 ≈ 28%; age 40 ≈ 20%; age 42 ≈ 10%; age 44 ≈ 5%. With donor eggs from a young donor, success rates are much higher (50–60%) regardless of the recipient's age, because the determining factor is the egg's age, not the uterus. Preimplantation genetic testing (PGT-A) identifies chromosomally normal embryos for transfer, which improves live birth rates per transfer especially for older women.

Understand how maternal age affects monthly fertility rates, conception probability, and pregnancy risks — based on published obstetric data.

⚕️ Medical disclaimer: This calculator provides population-level statistical estimates based on published research. It is not a diagnostic tool and does not constitute medical advice. Consult a licensed healthcare provider or reproductive endocrinologist for personalized guidance.

Maternal Age32 yrs

yrs

1855

Maternal Age32 yrs

yrs

1855

Cycles Tried (months of trying)6 cycles

cycles

136

Monthly Conception Rate

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Average Time to Conceive

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Probability in 12 Months

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Probability in 6 Months

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Miscarriage Risk

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Down Syndrome Risk

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ACOG Recommendation

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% Who Have Conceived by Now

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% Still Trying at This Point

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What This Means

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ACOG Recommendation

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🌸 What is Fertility by Age?

Fertility — specifically the ability to conceive a pregnancy — is profoundly influenced by maternal age. Women are born with their lifetime supply of eggs, roughly one to two million at birth, declining to approximately 300,000 at puberty and 25,000 at age 37. What matters for conception is not just the number of eggs (ovarian reserve) but their quality: the probability that any given egg is chromosomally normal and capable of becoming a viable pregnancy.

The key metric this calculator uses is the monthly fecundity rate: the probability of conception in a single menstrual cycle with regular unprotected intercourse, for a woman of a given age with no known fertility issues and a fertile male partner. At age 25, this rate is approximately 25–28% per cycle. It declines gradually through the early 30s, more steeply after 35, and significantly after 37–38. At 42, the monthly rate has fallen to roughly 5–6%.

From the monthly rate, the calculator derives the probability of conceiving within 6 and 12 months using the geometric formula P = 1 − (1 − monthly rate)^n. It also shows miscarriage risk and Down syndrome (Trisomy 21) risk by age — both of which increase with maternal age due to rising rates of chromosomal abnormalities in older eggs. The "Cycles Tried" mode uses the same formula in reverse, showing what fraction of women at your age would typically have conceived after a given number of cycles — providing statistical context for where you stand in the process.

Important: These are population-level statistical estimates based on published research (ACOG, CDC, peer-reviewed obstetric literature). They are not predictions for any individual. Actual fertility is influenced by many factors beyond age: ovarian reserve (best measured by AMH and antral follicle count), fallopian tube health, uterine anatomy, endometriosis, thyroid function, and male partner factors. If you have concerns about your fertility at any age, consulting a reproductive endocrinologist is the right step — never the wrong one.

📐 Formula

P(conceive within n cycles) = 1 − (1 − p)ⁿ

p = monthly fecundity rate for your age (probability per cycle)

n = number of cycles (months) of trying

Example: Age 32, p = 0.20, n = 6 cycles: P = 1 − (0.80)^6 = 1 − 0.262 = 73.8%

Why geometric? Each cycle is an independent event; the probability of NOT conceiving in all n cycles is (1−p)^n, so the probability of conceiving in at least one is 1 minus that.

Average Cycles to Conceive = 1 ÷ p

This is the expected value of a geometric distribution with success probability p

Example: Age 30, p = 0.23 → expected cycles = 1 ÷ 0.23 = 4.3 cycles on average

Note: The average is not the median — half of women will conceive faster than average, half slower.

📖 How to Use This Calculator

Steps

Choose a mode — 'Fertility by Age' shows your statistical profile at a given age: monthly rate, 6 and 12-month probabilities, miscarriage risk, and Down syndrome risk. 'Cycles Tried' shows how your current number of months trying compares to what's typical for your age.

Enter your maternal age — Drag the slider or type your age (18–55). The calculator uses the published monthly fecundity rate for each age band, based on ACOG guidelines and peer-reviewed fertility research.

Review the fertility profile — Monthly rate, average cycles to conceive, 6-month and 12-month probabilities, miscarriage risk, and Down syndrome risk are all shown. Use the ACOG recommendation to know when to seek specialist evaluation.

Use Cycles Tried for context (if applicable) — Switch modes, enter your age and the number of cycles you have been trying. The result shows what percentage of people at your age would typically have conceived by this point and provides a statistically informed interpretation.

💡 Example Calculations

Example 1 — Fertility Profile at Age 30

Maternal age: 30

Monthly fecundity rate at age 30: approximately 23% per cycle. Average cycles to conceive: 1 ÷ 0.23 ≈ 4.3 cycles (4–5 months on average).

Probability of conceiving within 6 months: 1 − (0.77)^6 = 1 − 0.208 = 79.2%. Within 12 months: 1 − (0.77)^12 = 1 − 0.043 = 95.7%.

Miscarriage risk ≈ 12% per confirmed pregnancy. Down syndrome risk: approximately 1 in 940 pregnancies. ACOG recommendation: try naturally for 12 months before evaluation.

Monthly rate: 23% — 12-month probability: 95.7% — Miscarriage risk: 12%

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Example 2 — Fertility Profile at Age 37

Maternal age: 37

Monthly fecundity rate at age 37: approximately 14% per cycle. Average cycles to conceive: 1 ÷ 0.14 ≈ 7.1 cycles on average.

Probability within 6 months: 1 − (0.86)^6 = 1 − 0.405 = 59.5%. Within 12 months: 1 − (0.86)^12 = 1 − 0.164 = 83.6%.

Miscarriage risk ≈ 17%. Down syndrome risk: approximately 1 in 274. ACOG recommendation: seek evaluation after 6 months of trying at age 35–37.

Monthly rate: 14% — 12-month probability: 83.6% — Miscarriage risk: 17%

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Example 3 — Cycles Tried: Age 35, Trying for 8 Months

Age 35 — 8 cycles tried

Monthly rate at 35: approximately 15%. Probability of conceiving within 8 cycles: 1 − (0.85)^8 = 1 − 0.272 = 72.8%.

That means 72.8% of women at age 35 would have conceived by now. The remaining 27.2% are still trying after 8 months — that is a substantial minority, but 8 months is still short of the 12-month average for this age group.

ACOG recommends evaluation after 6 months for women aged 35–37. At 8 months, the recommendation is to have already consulted a reproductive endocrinologist for initial workup (AMH, AFC, semen analysis).

72.8% would have conceived — 27.2% still trying — Seek evaluation now per ACOG

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❓ Frequently Asked Questions

How does age affect female fertility?

Female fertility declines with age because women are born with all the eggs they will ever have. Egg quantity and quality both decrease over time. The monthly fecundity rate is approximately 25–28% in the early 20s, 20–23% at age 30, 14–15% at 35–37, 10% at 38–39, 6% at 40–42, and 2–4% at 43–44. After 45, conception with one's own eggs is uncommon but possible.

What is the monthly fertility rate by age?

Based on ACOG estimates and published research: age 20–24 ≈ 25–28%/cycle; age 25–29 ≈ 22–25%; age 30–32 ≈ 20%; age 33–34 ≈ 18%; age 35–37 ≈ 14%; age 38–39 ≈ 10%; age 40–42 ≈ 6%; age 43–44 ≈ 4%; age 45–47 ≈ 2%; age 48+ ≈ 1%. These are population averages with significant individual variation.

What is the probability of getting pregnant within 12 months by age?

Using P = 1 − (1 − p)^12: age 25 ≈ 97%; age 30 ≈ 94%; age 35 ≈ 85%; age 38 ≈ 72%; age 40 ≈ 72%; age 42 ≈ 52%; age 45 ≈ 21%. These estimates apply to women with no known fertility issues and a fertile male partner. Individual rates vary significantly based on ovarian reserve, anatomy, and health.

At what age does female fertility start to decline?

Fertility declines gradually from the late 20s, more noticeably in the early 30s, and significantly after 35. The decline accelerates after 37–38. The most dramatic fall occurs between 40 and 45. However, these are population-level trends — individual women vary substantially, and ovarian reserve testing (AMH) provides a more personalized picture than age alone.

What is the miscarriage risk by age?

Miscarriage risk increases with maternal age due to rising chromosomal abnormality rates in eggs: under 30 ≈ 10%; age 30–34 ≈ 12%; age 35–37 ≈ 17%; age 38–40 ≈ 25%; age 41–44 ≈ 35%; age 45+ ≈ 50%. The majority of miscarriages at all ages are caused by chromosomal abnormalities unrelated to maternal health behaviors.

What is the Down syndrome risk by maternal age?

Down syndrome (Trisomy 21) risk per pregnancy: age 25 ≈ 1 in 1,250; age 30 ≈ 1 in 940; age 35 ≈ 1 in 350; age 38 ≈ 1 in 179; age 40 ≈ 1 in 100; age 42 ≈ 1 in 68; age 45 ≈ 1 in 30. Prenatal screening (NIPT, nuchal translucency, quad screen) can detect chromosomal conditions early in pregnancy.

When should I see a fertility specialist?

ACOG guidelines: under 35 — after 12 months of trying; age 35–37 — after 6 months; age 38 or older — after 3 months. Earlier evaluation is appropriate for anyone with irregular periods, prior pelvic infections, endometriosis, recurrent miscarriage, or a partner with known male factor infertility. Seeking evaluation early is never wrong.

Does the father's age affect fertility?

Yes. Sperm count, motility, and morphology decline gradually from the late 30s. More importantly, sperm DNA fragmentation increases with age, raising miscarriage risk. Male factor infertility accounts for 40–50% of all infertility cases regardless of age and should be evaluated early via semen analysis.

What fertility tests should I consider based on my age?

For women: AMH (Anti-Müllerian Hormone) and antral follicle count (AFC) measure ovarian reserve. Day 3 FSH and estradiol are additional markers. A hysterosalpingogram (HSG) checks fallopian tube patency. For men: semen analysis covers count, motility, and morphology. Both partners should be evaluated early — male factor is equally common.

How does IVF success rate vary by age?

Live birth rate per IVF transfer using own eggs: age 35 ≈ 40%; age 38 ≈ 28%; age 40 ≈ 20%; age 42 ≈ 10%; age 44 ≈ 5%. With donor eggs from a young donor, success rates are 50–60% regardless of recipient age — because egg age, not uterine age, is the primary determinant. Preimplantation genetic testing (PGT-A) can improve outcomes per transfer by identifying chromosomally normal embryos.

What lifestyle factors affect fertility by age?

Age is the dominant factor, but lifestyle matters: smoking accelerates ovarian aging; BMI outside 18.5–25 disrupts hormonal balance; excessive exercise can suppress ovulation; heavy alcohol and caffeine are associated with modestly reduced fertility. Prenatal vitamins with folic acid (400–800 mcg/day) should be started before trying to conceive.

Is it possible to get pregnant naturally after 40?

Yes — natural conception after 40 is possible, though monthly rates are lower (approximately 6–10% per cycle at 40). Many women in their early 40s conceive naturally. Miscarriage risk is higher when it occurs. ACOG recommends seeking evaluation after just 3 months of trying at age 38 or older, rather than waiting a full year, because of the accelerating age-related decline.

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📌 Quick Tips

💡Monthly fecundity rate (the probability of conception in a single cycle) declines gradually through the 20s and more steeply after 35. At 30, the rate is roughly 20–23%; at 38, approximately 10–14%; at 42, around 5–6%.

💡The 12-month conception probability is not simply 12× the monthly rate — it is a geometric calculation: P = 1 − (1 − monthly rate)^12. At 30 with a 20% monthly rate, the 12-month probability is 1 − 0.80^12 = 93.1%, not 240%.

💡ACOG guidelines recommend seeking fertility evaluation after 12 months of trying for women under 35, after 6 months for women 35–37, and after 3 months for women 38 and older. Earlier evaluation is never harmful and often valuable.

💡Miscarriage risk rises with age primarily because chromosomal errors (aneuploidy) in eggs increase with age. The miscarriage risk figures in this calculator (10% at 25, 25% at 40, 50% at 45+) align with population-level published estimates — individual risk varies.

💡This calculator provides statistical estimates based on published population data, not personalized medical advice. Actual fertility depends on many individual factors including ovarian reserve (AMH, antral follicle count), fallopian tube health, uterine anatomy, and partner factors.