Yeah that's the debate that always comes up. I haven't really heard a great answer yet.

On an individual level, people make decisions shaped by cost, hope for the future, social support, all that stuff. On a population level, the poorest countries have the most kids per capita; as far as I'm aware it's a strong correlation. If there are any non-fascist demographics nerds I'd like to hear some expert opinions on this contradiction.

But personally my opinion is that we should do the things that make people's lives better and give them more options, regardless of its impact on birth rate. The population level, and it's moderate increase or decrease, is only a problem because we live in a system that can't do any planning and is terrible at allocating resources. A hypothetical communist world system could work with basically any realistic population level. In the current system, the population shrinking (or growing, or changing demographics) at any realistic rate is not even a top-5 problem so why worry about it? We have war and genocide and fascism and climate change and tons of other urgent problems, I don't see why anyone would care so much about demographics unless they're huge racists or a certain sub-type of neoliberal nerd that thinks this will threaten markets over the long term (and somehow doesn't see any larger financial risks in the next several decades).