The steady rise in life expectancy in wealthy countries has slowed significantly, and new projections suggest that generations born after 1939 and up to the year 2000 will not, on average, live to be 100.
The findings come from a wide-ranging study published in the Proceedings of the National Academy of Sciences and conducted by researchers from the Max Planck Institute for Demographic Research in Germany, France’s National Institute for Demographic Studies (INED), and the University of Wisconsin–Madison.
The study analyzed extensive mortality data for birth cohorts across 23 high-income, low-mortality countries—including European nations, the United States, Japan, Canada, and Australia. Using advanced statistical models, researchers tracked long-term trends in life expectancy.
Results show that between 1900 and 1938, life expectancy rose by an average of about six months per generation. For those born after 1939, the pace slowed to less than half that—just two to three and a half months per generation.
The researchers point to near-total elimination of child mortality as a key driver of early 20th-century gains. Since then, improvements among children and young adults have slowed, and while advances at older ages continue, they are not enough to sustain previous momentum.
At the start of the 20th century, life expectancy surged: people born in 1900 lived to an average of 62, while those born in 1938 reached about 80. “If today’s generations had continued at the same pace as the first half of the 20th century, someone born in 1980 could have expected to live to 100,” said José Manuel Aburto, lead author and researcher at the Max Planck Institute.
Even under optimistic scenarios—such as doubling survival improvements among older adults—future life expectancy gains will remain far below those recorded in the early 1900s, the study concluded.
“Society and public policy must adapt to a new reality where progress continues but is more modest,” the report said. “The focus should not only be on how many years people live but also on the quality of those years.”
The authors stress that mortality forecasts are not certainties. Unforeseen events such as pandemics, new medical breakthroughs, or major social changes could shift outcomes dramatically. Still, they warn that the slowdown has wide implications for health, pension, and welfare systems in wealthy countries.
Rather than assume life expectancy will continue to rise at a rapid pace, governments should build policies based on more limited gains, the researchers argue. They recommend investing in chronic disease prevention, healthy aging, and long-term economic planning to prepare for the challenge ahead.