Key points from article :
Falling birth rates may not level off or recover on their own, according to a new analysis by Diane Coffey, Michael Geruso and Dean Spears at the University of Texas at Austin and Sangita Vyas at Hunter College in New York. Many population projections used by governments and international agencies assume that fertility in low-birth-rate countries will eventually stabilise or even rebound. The team found little evidence to support that assumption.
The researchers looked at several kinds of data: UN figures on fertility rates for every country from 1950 to 2023, the number of children actually born to women in 31 countries who were themselves born between 1935 and 1975, and local fertility rates within Japan, India and the US. Across all of them, places where fertility had fallen to low levels generally saw it keep falling, rather than settling at a stable level.
The authors acknowledge that some low-fertility countries saw birth rates pick up in the early 2000s, and say their analysis accounts for those earlier findings. They argue that the rebound assumptions built into widely used population projections should be treated as hypothetical and re-examined.
Falling birth rates are already reshaping populations. In the US, births have dropped by nearly a quarter since 2007, deaths now outnumber births in more than half of states, and older adults are expected to make up 23.4% of the population by 2060.
The study is a working paper that has not yet been peer reviewed. The authors say there is not yet enough data to draw firm conclusions, and that future research may identify factors their analysis did not capture. Population trends also depend on migration, which can offset the effects of low birth rates.
The research was led by Diane Coffey, Michael Geruso and Dean Spears at the University of Texas at Austin and Sangita Vyas at Hunter College, and published as a working paper by the National Bureau of Economic Research.
