According to a recent study, more than half of the babies now born in wealthy nations will live to be 100 if current life expectancy trends continue. Danish experts say that in the 20th century, most developed countries saw an increase in life expectancy of around 30 years. Advances in medical treatments also mean that the elderly face less serious disability and functional limitations as they age, allowing them to remain active for longer. A growing aging population could pose a challenge for health, economic, and social systems, but the study authors suggest that the elderly can help reduce this burden by maintaining a degree of employment into their old age.