The only proven solution is subsidized childcare, longer parental leave, individual taxation. This is an interesting comment to me, because I'm trying to think

The only proven solution is subsidized childcare, longer parental leave, individual taxation. This is an interesting comment to me, because I'm trying to think of example country pairs in which a country with subsidized childcare, longer parental leave, and individual taxation has a higher fertility rate than an otherwise similar country that lacks those things. The United States continues to have a higher fertility rate than many countries in Europe that have more subsidized childcare and longer mandated parental leave than the United States, for example, so I'm not sure that these public policy factors outdo the effect of other cultural and economic factors in either raising or lowering the country-wide fertility rate.