There are tons of studies and data that can be found in many places (obviously, it's a fairly common topic of research) but here's Wikipedia: https://en.wikiped

There are tons of studies and data that can be found in many places (obviously, it's a fairly common topic of research) but here's Wikipedia: https://en.wikipedia.org/wiki/Age_and_female_fertility https://en.wikipedia.org/wiki/Age_and_female_fertility They also have a table there, outlining the theoretical "percent of women who will fail to have a live birth" if they start trying to conceive at a certain age. Not the same thing as infertility -- they may be fertile, just unlucky up until the point that they're actually infertile. The numbers are a little all over the place, but for 35 year old women, it's somewhere between 13 and 22%