Idiocracy - the most intelligent opted not to breed and have been overtaken by the lower masses.
Read the article.
Increased birthrates won’t help the genetic fitness, although it WILL keep a population from shrinking in the “near term”.
It’s hopeless, humanly speaking.
It’s a matter of incentives... switch the incentives and you get a different outcome.
Watch this for our survival: https://www.youtube.com/watch?v=LPjzfGChGlE
High birth rates by the underclass only last while the welfare state supports them. Remove the welfare state, and suddenly the underclass women find it unworkable to have kids, and go back to their traditional role of being the housekeepers and nannies of the middle and upper classes.