Birthrates are dropping in developed nations. They've been low in Europe for years, and America fell behind replacement levels. Personally I think this is a direct response to wealth gaps, living costs, medical costs (at least in the US) and low wages. All of these things are a direct result of capitalism and centralization of wealth and power. So the actual solution is to redistribute wealth, tax the rich, and focus on social programs. But that would be anticapitalist, so instead we invent a fertility crisis.