Humanity isn't disappearing because people don't want babies.
Humanity is disappearing because having a baby costs $300,000 and 18 years of your life when you're already 30 and anxious about retirement.
Fix the economics. Birth rates fix themselves.
Every country that made parenting affordable France, Germany, Denmark stabilized their fertility rates.
Every country that didn't US, Japan, South Korea is collapsing demographically.
It's not a biology problem. It's a policy problem.