Part of the background to the current confusion about how long fertility lasts is the fact that there is very little good data. … The closest thing to a thoroughly controlled experiment of women’s fertility so far involved a Protestant religious sect called the Hutterites, pre-1950.
“Not that YOU Look Old…”
Women’s Labor and Infertility
But society as a whole benefits when all citizens who want them can have kids when they’re ready–at the most basic level because we need a next generation of workers, but at another level because we want our citizens to be happy–for charitable reasons and more pragmatically because families are often an important part of what people work for, at whatever point they start them.