It’s never at the same time and older siblings help with the younger ones which is still an infinitely better situation than some low paid employee watching 15 kids at the same time.
Also that time has passed. All of Asia including south and south east are basically at replacement rate. Africa averages higher but not by a whole lot more and that number is dropping quickly.
There’s a reason women from wealthy families never work and dedicate all their time to raising kids.
