Societies shift from high birth/death rates to low as they industrialize.
Thompson and Notestein's model, drawn from European data. Its policy consequence is that the fastest route to lower birth rates has historically been lower child mortality, which is counterintuitive to most people.
In practice
- Falling child mortality reliably precedes falling birth rates, which is why health spending is also population policy.
- A country's fertility falls fastest where girls' schooling rises, and the sequence has been the same across four continents.