On a more fundamental level, it's very understandable that many people look at the state of the world and their conclusion is not: "oh man one thing we definitely need is more people". It's not like we'll run out anytime soon.

If you really want to boost childbirths, give people some hope for tomorrow that we have any capacity to deal with the most immediate existential threats and that their children won't be hunting cockroaches in some Mad Max world.