Despite media hype for life extension, life expectancy gains are actually slowing down worldwide

Aug 29, 2025 | 0 comments

By Steve Fink

For more than a century, each generation has lived longer than the one before. Parents routinely outlived their parents, and children expected birthdays their grandparents never reached. But new research suggests this remarkable streak of rising lifespans may be running out of steam.

A study published in the Proceedings of the National Academy of Sciences shows that people born between 1939 and 2000 are on track to experience much slower gains in life expectancy compared to earlier generations. According to the findings, none of these groups are projected to reach an average lifespan of 100 years. It’s a sharp turn from earlier predictions that expected longevity to keep climbing.

Since the early 1900s, life expectancy in wealthy countries has risen by roughly 0.46 years with each new birth cohort. Many experts once believed that meant children born in the 1980s would routinely pass the century mark. Instead, the new forecasts show that improvement rates have slowed by 37 to 52 percent, depending on the method used.

What’s causing the life expectancy slowdown?
The slowdown isn’t because older adults are dying earlier. Rather, it stems from the fact that the huge gains of the 20th century came from saving young lives and those advances have already been achieved. More than half of the current slowdown can be traced to changes in mortality before age 5, and over two-thirds to changes before age 20.

“This pattern had already emerged in the observed data for the cohorts included in our analysis,” the researchers explain in their paper. “Thus, even if these estimates turned out to be overly pessimistic, it is unlikely that the deceleration will reverse in the near future.”

The research team, led by demographers at the University of Wisconsin, Max Planck Institute for Demographic Research, and collaborating institutions, studied mortality records from 23 high-income countries, including the United States, Japan, and most of Western Europe. They focused on “cohort life expectancy,” which follows the actual survival of people born in the same year.

That measure differs from the more familiar “period life expectancy,” which reflects mortality during a single calendar year. For example, a year like 2020, when COVID-19 deaths spiked, would give the impression of dramatically shorter lives. But people born in 2020 won’t spend their whole lives in a pandemic. Cohort measures give a truer sense of how long those people will actually live.

Using six forecasting methods, the researchers projected mortality for people born between 1939 and 2000. Every approach pointed to the same conclusion: the rapid improvements of the early 20th century will not continue at the same pace.

Longevity progress was ‘low-hanging fruit’
The study shows that much of humanity’s progress in extending life was the “low-hanging fruit” of the past century. Saving infants and children from infectious diseases, improving maternal care, and reducing accidents and violence drove the biggest leaps forward.

Take Switzerland: between 1900 and 1938, mortality improvements under age 5 accounted for 54 percent of all life expectancy gains, and when combined with ages 5 to 20, explained 70 percent of the progress.

Those benefits have now plateaued. In wealthy nations, deaths in childhood or early adulthood are rare. What remains are age-related killers such as cancer and heart disease, which have proven harder to eliminate.

Even if medical progress doubles the rate of future improvements, the study finds that gains would still fall far short of the earlier era. Most of the cohorts studied have yet to reach the ages where those medical advances would matter most, limiting their impact.

A global pattern across wealthy nations
The slowdown is not confined to a handful of countries or tied to specific crises like opioids or gun violence in the U.S. The same pattern appears across wealthy nations, including both those with the highest and middle-range life expectancies.

To check whether their methods might be biased, the researchers tested past forecasts against actual outcomes for people born between 1919 and 1938. While some methods slightly underestimated improvements, the bias was too small to account for the sharp slowdown now projected.

The trend is already visible in the observed data. Rather than a sudden break, it reflects limits that have been building for decades.

Why living to 100 will likely always be an exception to the rule
The study doesn’t argue that human lifespan has reached a biological ceiling. Instead, it shows that the mix of biology and society is making further dramatic progress harder to achieve. Other studies have noted that life expectancy in some developed countries has stalled in recent decades. This work extends that observation to whole generations.

Some demographers have held on to optimism, pointing out that progress has endured even through wars and pandemics. But by following actual birth cohorts, this research indicates that such optimism may not hold for people already alive today. Less sanguine researchers suggest that environmental factors such as the surge of microplastics and PFASs (forever chemicals) could soon begin to reverse the longevity trend.

For individuals, this doesn’t mean lives will be shorter than their parents’. On average, people will still outlive the previous generation. What’s changing is the pace: each new cohort is unlikely to enjoy the dramatic leaps in longevity seen in the 20th century.

For better or for worse, the extraordinary century of ever-rising life span, one of modern society’s most celebrated achievements, may be reaching its limits for those already born. Though many will fight to prove the study wrong, it seems the age of automatic, generation-to-generation longevity gains could be ending.
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Credit: StudyFinds