In the US, I would say affluence actually allows you to have children, if you want to provide them with life in a good school district and a single family home in a suburb close to burgeoning city. You have to borrow student loans, then work to save for a down payment, then save for childbirth and health expenses. Now you have structural costs of student loan debt repayment, mortgage debt repayment, daycare, property tax, retirement savings debt, and possible vehicle debt repayment. And now you’ve advanced in age, and you can only have 2 kids.