MPIDR Working Paper

Revisiting the J-shape: human development and fertility in the United States

MPIDR Working Paper WP-2023-022, 48 pages.
Rostock, Max Planck Institute for Demographic Research (May 2023)
Open Access


Economic and social development are closely linked with fertility. Several studies have shown that the relationship follows an inverse J-shape: at low and intermediate levels of development, the association is negative; and at high levels of development the association is reversed and becomes positive. However, more recent research building on subnational and U.S. data found only mixed evidence for the inverse J-shape. In this paper, we draw on subnational data on development and fertility in the U.S. states between 1969 and 2018 to examine the relationship between development and fertility. Using a longitudinal approach and addressing several criticisms of the fertility reversal hypothesis, our results support the inverse J-shaped pattern, reconciling trends observed in the U.S. with those in other high-income countries. We also discuss potential explanations for why studies might not detect the inverse J-shape. Moreover, our findings provide insights into the mechanisms that link development and fertility, showing that gender equality and economic uncertainty mediate the relationship between development and fertility.

Keywords: USA, economic and social development, fertility, fertility determinants
The Max Planck Institute for Demographic Research (MPIDR) in Rostock is one of the leading demographic research centers in the world. It's part of the Max Planck Society, the internationally renowned German research society.