https://sci-hub.hkvisa.net/10.2307/1972123
In a 1987 paper, it was estimated that raising the birth rate from 1.9 to 2.1 would cost $380 billion in social expenditure. That's about a trillion in 2023 dollars. But the birth rate is now 1.7, so assuming linearity, doubling the cost seems likely. 2 trillion dollars, which would be 2/7 of US govt expenditure. The population is 40% bigger so 2.8 trillion. This is about $28,000 per extra baby. It's likely an underestimate because americans are richer now.
