I'm all for paid maternal and paternal leave, free daycare, etc. etc., but these won't solve the birth rate issue. Such measures have been in place in countries such as Canada and most of Western Europe for a long time and they are even more reliant on immigration for population growth than the U.S., aren't they?
Add in the fact that the American economy relies heavily on small businesses, much moreso than Western Europe, Canada, etc. and you're talking about policies that the majority of American employers would be exempt from - thereby having even less impact. Unless we're also adding destroying small businesses into the equation here (which seems to be the unintended consequence of most well-intended legislation). This would be akin to pouring gasoline on our economy and lighting a match. That's going to have a significant impact on birth rates as well, but not for the better.
Educated people, on the whole, don't want more kids, and it's not significantly about finances. It's about lifestyle for the parents and the kids they do have. Religious people, generally speaking, are less educated than secular people. Many major religions actively push procreation as part of their message, for obvious reasons. The only thing that will spike a birth rate would be for a major religion to truly seize control, kill off the educated populace, and enforce their nonsense from the top down - almost the inverse of Mao's moves. Sign me up!
Here's a solution of the top of my head. Start paying educated couples for their embryos. Put otherwise healthy folks through IVF and have them squirt out 7-10 embryos a pop. Store the embryos and offer free immigration, or a pile of money, whatever, to anyone who will carry 2-3 to term. Maybe start a civil service program where girls get their college paid for if they go through a couple of pregnancies for the team. Blamo! Population growth guaranteed. Now the educated class is doing their part to add numbers without having to raise them. All we have to do now is figure out how to pay to raise all the new babies in a healthy manner that makes them contributing members to society. What could go wrong‽‽‽?‽‽‽
Or maybe, just maybe, our economy will adjust as populations decline, and while there will be bumps in the road (which will happen no matter what anyway) we resourceful humans will find a way to make it all work out just fine.