he US has been portrayed as in the grip of a maternal mortality crisis. In contrast to most other developed nations, the rate of maternal deaths in the US has been going up since the early 2000s.

But why? With the help of Saloni Dattani, a researcher at Our World in Data, Tim Harford explores how a gradual change in the way the data was gathered lies at the heart of the problem.

Presenter: Tim Harford