I see two outcomes.

The first, being a mother/parent is considered a legitimate career choice to be worth getting paid for. I envision women as saying "Well, I kind of do want a baby, and ill get paid money to do so, so that makes it worth it to me. Ill take some time off from my other job to do it." I also envision some women who really want to be mothers as saying "You want to pay me for being a mother and I get to retire at 65 without actually having worked in traditional employment? Thats my ideal job! *Has 7 kids*." The elderly are also incentivized to assist mothers in day to day labour.

The second is sadder. In society, a minimum number of people are required to get things to work. The fertility rate lessens the amount of people in the world to such an extent that we are not longer able to keep our modern lifestyle functional. The economy suffers, we aren't able to make as much stuff, and we regress back into a poorer economy. We do not go extinct, but we suffer major economic harm such that having kids is suddenly now an economic gain, and the fertility rate rises again.

The most realistic scenario is just a blurring of the two. We suffer economic harm, and benefits to mothers increases substantially.