Or, crazy idea, we make life livable for the locals and then we incentivize them to have kids of their own? And before you say it, I'm an immigrant from the 3rd world myself. I'm not anti-immigratiom, but the birth rate talking point is a very poor one.

Not to mention how unsustainable it is anyways, what happens a few years down the line when the immigrants stop having kids? There isn't an infinite ocean of people you can import on a whim, and definitely not forever.

I don't care about US immigration, but remember that people don't want to have more children. There's nothing related with costs or whatever. Norway have a lot of incentives and people still prefer to have less kids than USA. If these "livable conditions" were a true argument, rich countries would not need to incentivize people, because they would have more children willingly. Life is way more livable in a rich country than a poor country