I think it's also because high middle class earners are financially smart (don't buy things if they don't have the money), AND health-smart (realize their body's needs, including sleep) so they choose logically not to have kids, because they do not have the resources for it, and will not sacrifice their own well-being just to have kids.
The upper class is financially smart, AND has the resources (20+ years of child rearing costs already secured upfront, ability to hire night nannies, ability to take a few years away from work without income, own a home and not at the mercy of rent increases), so they have kids.
The lower class is often not financially smart, is not health smart, and systematically poisoned to sacrifice themselves and buy things they cannot afford. They are given insufficient resources and told that they should have kids, so they do.
The lower class is often not financially smart, is not health smart, and systematically poisoned to buy things they cannot afford, including kids, so they have kids.
i don't believe that is true.
raising kids is not that expensive. what is expensive is the high expectations for what you should spend on your kids with that middle class and high earners have. like sending kids to college.