Following mid-20th century predictions of Malthusian catastrophe\, fertility in the developing world more than halved\, while living standards more than doubled. We analyze how fertility change related to economic growth during this episode\, using data on 2.3 million women from 255 house- hold surveys. We find different responses to fluctuations and long-run growth\, both heterogeneous over the lifecycle. Fertility was procyclical but declined and delayed with long-run growth\; fluctuations late (but not early) in the reproductive period affected lifetime fertility. The results are consistent with models of the escape from the Malthusian trap\, extended with a lifecycle and liquidity constraints. \;