The society first has to provide for its citizens instead of giving socialism to billionaires instead of a proper social safety net, or they won't want to or can't have kids.
I think the solution might be in taxes. No kid;you are taxed at 60% , one kid 50% two kids 40 % and three kids 30 % . 20 % for anyone with more than four kids.
VAT on people with kids 12.5 %