(CNN) — Life expectancy fell across the majority of high-income countries, signaling a collective and simultaneous decline among affluent nations for the first time in decades, a new study finds.

After more than a century of steady progress, new research warns that the world’s life expectancy boom is slowing, largely because improvements in early-life mortality have already been achieved.

Life expectancy for women varies considerably from country to country, and while science has yet to discover the magic secret to living forever, some countries seem to know a lot about the recipe for ...