A new study says the number of elderly people around the world is growing faster than any other age group, and could reach 1 billion within the next 10 years.

The study, titled Aging in the Twenty-first Century: A Celebration and a Challenge, was issued this week by the United Nations Population fund. It says that in the year 2000, for the first time in history, there were more people age 60 and older than there were children under 5.

Demographers say that by 2050, the older generation will be larger than the under-15 population. In just 10 years, the number of older persons will surpass 1 billion people, an increase of close to 200 million people over the decade.

The new report underlines that, while the trend of aging societies is a cause for celebration, it also presents huge challenges for health care and retirement systems, living arrangements and intergenerational relations.

Analysts say aging populations may pose much greater challenges for developing countries where poverty pressures already strain public budgets.