> there's a reason authoritarians across the world are banning abortion and targeting birth control

I don’t think that’s because of birth rate decline. While authoritarians give lip service to that occasionally, it’s never their primary cited reason (which is usually some combo of religion, purported return to “traditional” prosperity via reduced promiscuity, aggression against feminist political opponents, etc). Also, most authoritarians aren’t that long-term in their goals.