Economic prosperity and fertility?

A cycle to which we may now be prone:

1. Rising income causes fertility to plummet.
2. A few generations later, plummeting fertility causes the economy to collapse.
3. Centuries are required to rebuild, because economic progress isn’t automatic, and because economic collapse generally does terrible things to our institutions, knowledge, morale, and understanding of economics. But eventually we do rebuild.
4. Incomes rise. Go to 1.