A different perspective from Poland: house affordability is equally as bad, so the argument could have been "young people don't have babies because they can't afford three bedroom apartments". But the country had a major baby boom in the 80s, during a (relatively mild) civil war and in the middle of a major economic crisis, when getting anything other than vinegar was a huge problem. And I clearly remember ppl living with 3 kids in studio apartments, playing with a lot of kids while waiting in mile long-lines for totally mundane rationed foodstuffs, school classes starting at 2 pm and ending at 8pm (too many kids), and my parents reaching out via their network to a director of orthopedic shoe factory because even money couldn't get you that kind of stuff. And in the 40 years since we had sustained growth rates comparable only to China or South Korea, and similar problems with childbirths. I don't buy any economic arguments.