Same goes with employment.
All this depends on future demographic trends - and assumes huge population growth is possible. It may not be. We may run out of available water, or energy, or some other necessary resource. What then?
So are the welfare programs. Can you imagine a girl of the "welfare class" contimplating getting pregnant, if she would have to support herself and the baby, by her own earnings at McDonalds/whatever? End all the various welfare programs, and the birth rate among the underclass would plummet.
Birth rates go down as societal wealth goes up. More precisely, in a society where a couple HAS TO have lots of kids in order to ensure that there will be somebody to look after them in their old age, they will have lots of kids. Where a couple can count on Social Security and investments in their old age, kids are an economic liability.
To understand why a society is going in a particular direction, you need to discover and understand the underlying incentive system