There are two competing factors: how much of a choice do women have and the opportunity cost of that choice?

If you look at the data, in rich countries much of the drop has been the reduction of unintentional teen pregnancies: women have better knowledge of and access to contraception, and they know that their lives will be better off from taking advantage of advanced education and building a career before having children.

Unless we’re talking about taking away the basic human right of bodily autonomy, that means that everything else must, as OP highlighted, focus on removing the negatives. This has to be done comprehensively to work: if, say, you provide free daycare but it runs 8-4, a professional parent probably isn’t going to change their estimate of the costs of having a child much at all since it’s still disruptive in ways which likely affect their long-term career trajectory. The richer the country, the more that matters: higher income is paired with higher cost of living and more opportunities which will be harder to take advantage of as a parent.