I just saw on twitter someone claiming that we "don't know how to raise the birth rate". No need to link them, it's a fairly common sentiment.
Have you actually tried raising the birth rate? For real, as in actually put in any effort?
Let's run the numbers on the stupidest possible thing that could work. Offer anyone who has a baby 50,000 dollars, tax free, no questions asked.
The median household income in the USA post tax is under 70,000 dollars. 50,000 dollars is a life changing amount for a large percentage of Americans. I would be shocked if a policy like this didn't send birth rates through the roof. Heck, I earn way more than that and I'd probably have more kids with a policy like that!
So how much would it cost?
There's about 3.5 million births a year in the USA. That comes to 175 billion dollars, or 3% of the federal budget. Even if the policy is incredibly successful and doubles birth, that comes to 6% of the federal budget.
That's about half of defense spending. It seems to me that ensuring the country has a future in 30 years is at least as valuable as maintaining the pax Americana. Even more it's a prerequisite to do so, unless we've invented robot soldiers by then.
Not convinced it would work? So test it out! Pick 20 counties randomly by lottery to implement this policy for, for 5 years. If it works well expand to the whole country.
But no, we've got no clue how to raise the birth rate, nothing to be done here, let's all go extinct.
Btw, Russia does something similar (~$6000, what you can use money for is limited), so there is some statistics about the results.