Revisiting the J-Shape: Human Development and Fertility in the United States

Area of Science:

• Demography
• Sociology
• Economics

Background:

• Fertility rates are intrinsically linked to economic and social development.
• The traditional inverse J-shape hypothesis suggests a negative association at lower development levels, reversing to positive at higher levels.
• Recent studies have presented mixed evidence regarding the inverse J-shape, prompting further investigation.

Purpose of the Study:

• To examine the relationship between economic development and fertility using longitudinal U.S. subnational data.
• To address criticisms of the fertility reversal hypothesis and test its validity.
• To explore mediating factors such as gender equality and economic uncertainty.

Main Methods:

• Longitudinal analysis of subnational data on development and fertility in U.S. states from 1969 to 2018.
• Statistical modeling to assess the inverse J-shaped pattern.
• Mediation analysis to identify the roles of gender equality and economic uncertainty.

Main Results:

• The study generally supports the inverse J-shaped relationship between development and fertility across most model specifications.
• Evidence suggests this pattern may have weakened or disappeared since the 2007-2008 financial crisis.
• Gender equality and economic uncertainty were identified as significant mediators in the development-fertility relationship.

Conclusions:

• The inverse J-shaped pattern between economic development and fertility holds under most conditions, but its persistence is questionable in recent times.
• The findings highlight the complex interplay of socioeconomic factors, particularly gender equality and economic stability, in shaping fertility trends.
• Further research is needed to understand the evolving dynamics of fertility in high-income countries amidst changing economic landscapes.