Honestly, I think at some level, the issue is that raising a child is labor- a lot of it, and it's work that needs to be done full time (hence why when neither parent can be home, kids are generally sent to daycare or school depending on their age), but which is also unpaid. A lot of people probably won't like this, because it would be a huge government expenditure that would require higher taxes on everyone not benefitting, and people would probably object to paying for other people's kids, but I think to really fix this, we need to pay a parent from each family that has them to stay home and take care of their kids. And not to the degree we currently do, I mean an entire, living wage income, with no requirement for any other kind of work for that parent (indeed possibly the opposite, since the entire point is to treat raising that person's family as their adequately compensated full time job). Leave it up to the parents involved which one of them is the one to do this, have the system be flexible to allow for the family to switch which parent is taking on this role if they want or need to, and increase the amount a bit with multiple kids to deal with increased cost of supplies and such.

Basically, I think that to really fix this, the system needs to be set up so that the cost of having and actually raising and being there for a kid is offset entirely, such that the decision to have one has no financial impact on a family at all.