There isn't a good way to boost fertility that I know of. The Nordics with very generous maternity leave and social safety net have a lower fertility rate than the USA.
I don't think fertility rate is something good or bad, I think people are very conservative (beyond its political sympathy) because change opens for uncertainty. It does not matter if it is about drugs, fertility, AI or diversity. Ergo, in many societies we live thinking that we are always progressing towards positive outcomes when the long term reality is more random.
Reduce taxes. All countries with high fiscal pressure have a low birth rate. Maybe the correlation is there. Someone out there might not want to look because his whole structure (bureaucracy) depends on the status quo.