@GalileoGirl: I do think that the two standards of emotional and financial readiness change in different times and places, but those are still the same standards. In the 50’s, I think people grew up earlier, and there were some well-paying jobs that you didn’t need an advanced degree to obtain. People could legitimately have kids earlier for this reason, and the ages your students cite seem to mesh with this idea.
Nowadays there’s a kind of “adultolescence” that twentysomethings go through, whereas they didn’t necessarily do that in the 50’s. Kids remain dependant longer, perhaps taking five or more years to graduate with a traditional four year degree (now imperative for a child-supporting job), and some even move back home after graduation until they’ve saved up enough to live on their own. (I think a lot of this has to do with manufacturing jobs that used to pay a living wage, but were moved overseas as a way for the company to save money.)
For their part, boys are becoming much slower to grow up. In the 50’s, you could expect a 25-year-old man to be married and have a career underway. Nowadays, a 25-year-old boy still wants to play with his XBox and play D&D on the weekends.
The twenties are the new late-teens, and the thirties are the new twenties. If this trend continues, people will be emotionally and financially ready to bear children about the time their gametes peter out.