I think their argument is valid because in the whole history of the world we were able to replace the population and had zero hospitals, right up to recently. S

I think their argument is valid because in the whole history of the world we were able to replace the population and had zero hospitals, right up to recently. So their argument stands, medical care is neither here nor there when discussing population replacement. Whoever wants kids just would do what they always did, have a few more because half will die before they hit 12.