Most fertility-encouraging policies that I've seen pay the same amount of money for the 1st/2nd/3rd/etc child. However it seems like a more efficient policy would pay exponentially larger amounts of money for every additional child, so the structure would look like:
- First child: $1k
- Second child: $2k
- Third child: $4k
- Tenth+ child: $512k
This would push parents to have more children, as each subsequent child would be cheaper to raise than the previous one. But the vast majority of parents would not end up having 10+ children, so this should be sustainable for the state budget. Have there been any discussions of a similar proposals in countries suffering from low fertility rates?