Female Fertility by Age Calculator

Female fertility changes with age — gradually from about 32, and faster after 37. Enter your age to see the share of women in that band who conceived within 12 cycles of trying, in a North American cohort study. It’s a population figure, not a prediction about you.

Why fertility declines with age

A woman is born with a fixed number of eggs, which falls over her lifetime in both quantity and quality. StatPearls traces the arc: oocyte numbers peak in utero and decline steadily until about age 32, drop faster until 37, and faster still after that. The joint ACOG–ASRM committee opinion says the same thing about the outcome that matters: “the fecundity of women decreases gradually but significantly beginning approximately at age 32 years and decreases more rapidly after age 37 years.”

Note what that replaces. The round numbers usually repeated — a decline “from 30”, a cliff “at 35” — are not what the U.S. guideline says. Thirty-five is the age at which evaluation is brought forward to 6 months, not the age at which fertility falls off.

What the numbers actually are

We used to show a per-cycle percentage for each age band. We removed it: no open U.S. source publishes one, and a table of invented precision is worse than no table. What does exist is PRESTO, a preconception cohort of 2,962 U.S. and Canadian couples with no history of infertility, followed for up to 12 cycles. These are cumulative chances of conceiving, not per-cycle odds:

Female age	Conceived within 6 cycles	Conceived within 12 cycles
21 to 24 years	56.8%	70.8%
25 to 27 years	59.0%	79.3%
28 to 30 years	62.0%	77.9%
31 to 33 years	60.7%	76.6%
34 to 36 years	55.9%	74.8%
37 to 39 years	46.3%	67.4%
40 to 45 years	27.6%	55.5%

Two things are worth reading off this table. The decline is real but not a cliff — most women in their late 30s conceived within a year. And the drop shows up earlier in the 6-cycle column than in the 12-cycle one: age costs speed before it costs the outcome. Adjusted for other factors, the per-cycle chance at 40 to 45 was 0.40 times that at 21 to 24, which matches ASRM’s summary that “relative fertility is decreased by about half at age 40 compared with women in their late 20s and early 30s.”

The oldest band stops at 45, and the study had few couples in it (38 women), so the confidence interval is wide — 30.7% to 80.2% at 12 cycles. Above 45 there is no figure here to give.

What to do with this information

Age is an important factor, but not the only one. If you’re planning to conceive, a few steps help:

• Know your fertile window — see the fertile window calculator.
• Remember fertility is a couple’s matter — see the fertile window calculator: male factor.
• If attempts continue for a while, check when to seek evaluation with the trying-to-conceive calculator. ACOG and ASRM recommend an expedited evaluation after 6 months for women older than 35, and StatPearls advises a reproductive endocrinologist for anyone 40 or older seeking fertility care.

This calculator is informational and shows population-level estimates. To evaluate your individual fertility, see a gynecologist or reproductive specialist.