[zozbot123]

> I don't know of a single political measure which has significantly raise birth rates.

Economic freedom, and getting rid of pervasive and extreme rent-seeking (especially at the local level) which raises the cost of caring for kids, and for the kids themselves to start a new household when they grow up. You can see this in places as different politically as the Scandinavian countries (e.g. Denmark), and the U.S. "Red" states. It just works, it's simply anathema in every way to all sorts of out-of-touch elites.

[bayesian_horse]

You're not citing facts, just anecdotes. It's hard to argue that Denmark is seeing a long-term rise in birth rates, let alone attribute that to any one such factor. And guess what, Denmark had a lot of immigration...

As for the US "Red" states it gets even more complicated, and part of that equation is the religiosity and that those who can afford it, and maybe would have fewer children anyway, just flee those areas in mass...