πΈ Fertility by Age Calculator
What the population data says about age and conception.
For informational purposes only, not medical advice. Consult a healthcare professional.
At 34, the monthly conception probability is roughly 16% per cycle, giving about an 87% cumulative chance over 12 months of well-timed trying, with miscarriage risk near 15% if pregnancy occurs. At 40, the monthly figure falls to about 6% and miscarriage risk rises toward 35%. Enter an age for the full picture.
How to Use This Calculator
These are population averages from demographic and clinical studies, assuming regular ovulation and well-timed intercourse. They describe groups, not your personal odds.
Enter the female partner's age. Age is the dominant variable; male age matters less but increasingly after 40.
Set the months of trying for the cumulative figure. Twelve months is the standard infertility-evaluation threshold under 35; six months at 35+.
Read the per-cycle odds, the cumulative conception chance, the miscarriage risk, and the combined live-birth estimate. Use them for planning and timing decisions, not as predictions.
Where the Numbers Come From
The per-cycle figures come from prospective studies of couples trying to conceive (Dunson et al. and large demographic datasets), and the miscarriage curve from obstetric cohorts showing aneuploidy-driven loss rising with age. The cumulative math assumes independent cycles, which is approximately true. The biology behind the decline: women are born with their lifetime egg supply, and both quantity (ovarian reserve) and quality (chromosomal normality) fall, with quality falling faster after 35. By 40, the majority of embryos are aneuploid, which is why miscarriage, rather than only conception failure, drives the age effect.
Worked Example
Age 34: monthly p = 0.16. Over 12 months: 1 β (0.84)^12 = 1 β 0.123 = 87.7%. Miscarriage risk ~15%, so approximate live-birth chance over the year β 87.7% Γ 0.85 β 74.5%. Age 40: p = 0.06, 12-month cumulative = 1 β (0.94)^12 = 52.3%, miscarriage ~35%, live-birth β 34%. Age 28: p = 0.22, cumulative 94.7%, miscarriage ~12%, live-birth β 83%. The calculator performs this same arithmetic. Notice that at 40 the bigger problem is less about conceiving and more about carrying: the miscarriage multiplier takes a third off the top.
What Moves Your Personal Odds
| Factor | Effect |
|---|---|
| Timing (fertile window) | Intercourse in the 3 days before ovulation maximizes odds; daily vs every-other-day barely differs |
| Weight | BMI under 18.5 or over 30 impairs ovulation and outcomes |
| Smoking | Accelerates ovarian aging; quitting restores much of the loss |
| Ovarian reserve (AMH, AFC) | Predicts response to stimulation, less predictive of natural conception |
| Male factor | ~40-50% of infertility involves male factors; semen analysis is cheap and easy |
| Duration trying | Each unsuccessful year lowers subsequent odds; seek evaluation at 12 mo (under 35) or 6 mo (35+) |
The evaluation thresholds exist because time is fertility: waiting two years at 38 costs more than at 28. A basic workup (ovulation confirmation, tubal patency, semen analysis, ovarian reserve) finds a treatable cause surprisingly often. For timing intercourse, our ovulation calculator identifies the fertile window, and for the preservation alternative, our egg freezing calculator shows what banking eggs at your age buys. Lifestyle moves the needle modestly but really: smoking cessation and weight normalization are the two with the best evidence.
The Other Side of the Curve
Declining fertility cuts both ways: contraception remains necessary until menopause is confirmed (12 months without a period), because the 1-3% monthly odds at 43-44 still produce real pregnancies. Unplanned pregnancy at 44 is rarer but higher-risk, which is why guidelines keep contraception counseling going through the late 40s. Perimenopause brings irregular ovulation that makes timing-based methods unreliable; long-acting methods suit this stage well.
A Note on the Emotional Math
Population percentages can feel cold when months of negative tests accumulate. Two truths coexist: most couples in their early 30s conceive within a year, and the minority who do not deserve evaluation, not more waiting. If you have passed the threshold (12 months under 35, 6 months at 35+), a fertility workup is the evidence-based next step, and modern treatment helps most couples who seek it. The numbers inform the plan; they do not define your story.
When the Numbers Argue for Acting Sooner
The steepest part of the fertility curve is also where waiting costs the most. A 36-year-old with 6 months of trying has better treatment prospects than the same person at 38 after two years of waiting, because ovarian reserve and egg quality only move one direction. Fertility preservation follows the same logic: freezing at 34 beats freezing at 38 on both odds and cost, as our egg freezing calculator shows. None of this means panic at 35; most 35-year-olds conceive without help. It means treating time as the resource it is: evaluate on schedule, preserve earlier rather than later, and make the big decisions with the curve in view rather than discovering it afterward.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What are the chances of getting pregnant at 35?
About 12-16% per cycle (16% at 34, 12% at 35-37 in population data), roughly 80-87% cumulative over 12 months of well-timed trying. Miscarriage risk is around 15-20% at this age.
At what age does female fertility decline?
Gradually from the late 20s, more noticeably after 32, and sharply after 37. The decline is driven by falling egg quantity and even more by egg quality (chromosomal normality).
What are the chances of pregnancy at 40?
About 6% per cycle, ~52% cumulative over 12 months, with miscarriage risk near 35%. Many 40-year-olds conceive, but evaluation after 6 months of trying is recommended rather than waiting a year.
Can you get pregnant at 45 naturally?
Rarely: monthly odds are around 1% and miscarriage risk exceeds 50%. Natural pregnancies at 45+ do occur but are uncommon; donor eggs are the usual path for those pursuing pregnancy at this age.
How long should we try before seeing a doctor?
12 months under age 35, 6 months at 35+, or sooner with known issues (irregular cycles, endometriosis, prior pelvic infection, male factors). Earlier evaluation is always reasonable if you are worried.
Does male age affect fertility?
Yes, modestly: semen parameters decline after 40 and time-to-pregnancy lengthens, with some increase in miscarriage and genetic risks after 45-50. The female age effect is much larger.
What is the most fertile time of the cycle?
The 3 days before ovulation through ovulation day, with the day before ovulation the single best. Sperm survive up to 5 days; the egg survives about 24 hours.
Does AMH predict natural fertility?
Weakly. AMH reflects ovarian reserve (egg quantity) and predicts IVF stimulation response well, but studies show it predicts natural conception poorly in the general population. Do not treat a low AMH as a verdict.
How does weight affect fertility?
BMI below 18.5 or above 30 impairs ovulation and fertility in women; obesity also affects male fertility. Modest weight normalization restores ovulation in many cases.
What is the miscarriage risk by age?
Roughly 10-15% under 30, ~20% at 35-37, ~25-35% at 38-41, ~50% at 42-44, and higher after 45. Most are due to chromosomal errors that rise steeply with age.