Chance of Pregnancy by Age
How likely is pregnancy within 6 months and within 12 months of trying, at your age? These are the published numbers from 2,962 couples in the United States and Canada.[1]
Every age group
Share of women pregnant within 6 and 12 cycles of trying, by age. A cycle is about one month. Your age group is highlighted.[1]
Why the youngest group is not on top. These are the raw numbers. Women aged 21 to 24 in this study more often had irregular cycles, lower incomes and less education, and those factors also affect fertility. After the researchers adjusted for them, the chance of pregnancy each month fell steadily with age. It was fairly stable from 28 to 33 and then dropped: compared with women aged 21 to 24, it was 0.82 times as high at 34 to 36, 0.60 times at 37 to 39 and 0.40 times at 40 to 45.[1]
ACOG and the American Society for Reproductive Medicine describe the same pattern: fertility "decreases gradually but significantly beginning approximately at age 32 years and decreases more rapidly after age 37 years."[3]
If it is taking longer
Not being pregnant after a year does not mean you cannot get pregnant. A European study of 782 couples estimated:[2]
| Woman's age | Not pregnant after 12 cycles |
|---|---|
| 19 to 26 | 8% |
| 27 to 34 | 13 to 14% |
| 35 to 39 | 18% |
Of the couples not pregnant after a year, an estimated 43 to 63% would conceive if they tried for another year, depending on age. Only about 1% of couples were completely unable to conceive, at any age. The authors concluded that fertility falls with age because the chance each month drops, not because more couples become sterile.[2]
The man's age. In the North American study, the man's age made little difference once the woman's age was taken into account, but few men were older than 45.[1] In the European study, the man's age started to matter in the late 30s: the share of couples not pregnant within 12 cycles rose from an estimated 18% to 28% between male ages 35 and 40.[2]
When to see a doctor
ACOG recommends an infertility evaluation at these points.[4]
The man matters as much as the woman. A male factor is part of the problem in 40 to 50% of couples with infertility, so ACOG advises looking at the male partner from the start, including a semen analysis.[4]
What does not predict it
Many women are offered an AMH blood test to "check their fertility." In a study of 750 women aged 30 to 44 trying to conceive naturally, women with low AMH (below 0.7 ng/mL) were not less likely to get pregnant: 65% were pregnant within 6 cycles, compared with 62% of women with normal AMH, and 84% compared with 75% within 12 cycles. High FSH did not predict lower fertility either. The authors concluded that these tests should not be used to judge natural fertility.[5]
The math behind it
Per cycle and cumulative are different numbers. The chance of pregnancy in any one month is much lower than the chance over a year, because each new month is another try. The numbers above are cumulative: the share of women who became pregnant at any point within 6 or 12 cycles.
After 6 months without pregnancy, the chance for the next 6 months is calculated from the same published numbers:
This is lower than the chance at the start, because couples who conceive easily are already pregnant. The ones still trying include more with lower fertility. The result is arithmetic on the published figures and carries more uncertainty than the figures themselves.
These are pregnancies, not births. Some pregnancies end in miscarriage, and the risk of miscarriage also rises with age. See the Miscarriage Risk Calculator.
Who was studied. Women aged 21 to 45 in the United States and Canada who had been trying for 3 cycles or less when they joined, had no history of infertility and were not using fertility treatment. Your own chance can be higher or lower. The 40 to 45 group included only 38 women, so its numbers are the least certain.[1]