More than half of the babies born today in rich countries will live to 100 years if current trends of life expectancy continue, a study appearing in the medical journal The Lancet said on Friday.
In the 20th century, most developed countries saw an increase of around 30 years in life expectancy, according to the paper led by Kaare Christensen, a professor at the Danish Ageing Research Centre at the University of Southern Denmark.
In 1950, only 15-16 percent of 80-year-old women, and just 12 percent of octogenarian men, made it to the age of 90 in advanced economies.
In 2002, this had risen to 37 percent and 25 percent respectively. In Japan, the survival rate from 80 to 90 is now more than 50 percent for women.
"If the pace of increase in life expectancy in developed countries over the past two centuries continues through the 21st century, most babies born since 2000 in France, Germany, Italy, the UK, the USA, Canada, Japan and other countries with long life expectancies will celebrate their 100th birthdays," the review said.
Evidence also suggests that, today, the extra years are less encumbered by disabilities and dependence than in the past.
The paper warned, though, that longer lifespans pose major social, economic and medical challenges as the very elderly become a greater proportion of the community.
One solution could be to spread employment more evenly across populations and ages of life, the authors said.
Instead of working for a long, intense spell and then retiring, "individuals could combine work, education, leisure and child-rearing in varying amounts at different ages."
"The 20th century was a century of redistribution of income. The 21st century could be a century of redistribution of work," they argued.