That's the word from the Census and Statistics Department, which said yesterday the average lifespan for women in Hong Kong may exceed 90 years in 2039, while men's lives will increase by 3.9 years to 83.7 years in 2039. That means 28 percent of the population will be elderly.

The department projects that women will live for an average 90.1 years, even longer than females in Japan, Sweden and Britain.

Last year, the average lifespan of Hong Kong women trailed those in Japan by 0.2 years, reaching 86.1 years.

Hong Kong men will also live longer than males in those countries.

The figures sparked calls for the government to study how to ensure adequate retirement benefits and health care for an aging population. "Many people are getting more health- conscious and trying to keep fit. It is a progress in social civilization," said Commissioner for Census and Statistics Fung Hing-wang.

In 2039, the department says, 28 percent of the 8.89 million population will be aged 65 or older. Last year, only 12.8 percent of the seven million people in the city were in that age group. The median age will rise to 47.6 in from 40.7 last year.

The department's previous estimate - made in 2007 - estimated 26 percent of the population would be aged 65 or above in 2036. This year, it adjusted the prediction to 27 percent by 2036. Fung attributed the growing aged population in part to the increase in overall life expectancy, the baby boom in the 1950s and an influx of young mainland immigrants in the 1970s and 1980s.

Fung said the city's sustainable development will hinge on whether its labor force can boost its productivity, whether the city can open up new areas for economic growth and whether it can attract more young people to settle.

The department expects that, from mid-2038 to mid-2039, 43,000 babies of mainland parents will be born in Hong Kong. Another 6,500 babies will be delivered by mainland mothers with Hong Kong husbands. They will make up 55 percent of the estimated 89,300 births in the city during that period.

Wong Hung, associate professor at the Chinese University's department of social work, said babies born to mainland women in Hong Kong and the immigration of mainlanders have helped ease the aging problem to some extent. But he urged the government to plan ahead on retirement benefits.

Nelson Chow Wing-sun, chair professor at the University of Hong Kong's department of social work and social administration, said the government should study how to help elderly people get medical insurance and how to provide them with long-term health care and social support.

The Census Department also predicted that the population imbalance between men and women in Hong Kong will worsen in the next 30 years. In 2039, there could be 1,000 women to 744 men. Last year, there were 1,000 women to 889 men.