Singaporeans are living longer and not having enough babies to replace themselves, meaning the swiftly ageing population has fewer working citizens supporting the growing pool of elderly.
These worrying trends, which emerged from the latest population figures released yesterday, can exert significant pressure on Singapore's economy, society and governance in future, said experts. They added that those working may have to toil longer and pay more taxes, and the Government will need to invest more in elder-friendly facilities.
These will be in demand by a growing number of Singaporeans, with those aged 65 and above forming 11.7 per cent of the citizen population this year, up from 7.8 per cent in 2002.
This year's Population in Brief report also showed that the old-age support ratio - which is the number of citizens in the working age band of 20 to 64 needed to support one older citizen - is decreasing rapidly.
It has fallen from 8.4 in 2000 to 5.5 today. But a better picture emerges when permanent residents are included, with the ratio at 6.4 this year, down from 8.7 in 2002.
According to World Bank data, Singapore has the highest proportion of older residents and the fastest ageing population in South-east Asia.
It is greying much faster than other developed nations such as Australia, the United States and most European countries, though the rate is on a par with Hong Kong's and slower than Japan's and South Korea's.
Economists and demographers say this will mean greater demand for health care and eldercare services, and elder-friendly infrastructure such as barrier-free accessibility features in transport and housing.
DBS economist Irvin Seah said that with the Government inevitably spending more, it will mean a "heavier financial burden on the working population, which in turn may mean higher taxes".
But Ms Selena Ling of OCBC said that the state may continue with its redistributive tax model, where the rich pay more through wealth and asset taxes.
"Singapore has been financially prudent, we can afford to draw down on our reserves as well," the economist added.
An ageing population will also require a slight "reorientation" of the economy, she said. This would involve a greater focus on developing medical services and attracting more workers to the sector, as well as increasing productivity and the use of technology in jobs so that people can continue to work as they age.
Still, some population statistics gave cause for cheer. More Singaporeans are getting married, with 23,192 marriages involving at least one citizen last year, up from 22,712 the year before.
Singapore residents are also continuing to have more babies. After hitting an all-time low of 1.15 in 2010, the total fertility rate (TFR) was 1.2 in 2011, and 1.29 in last year's Dragon Year - though it is still below the replacement rate of 2.1.
This upward trend was seen across all three major races, with the biggest increase among the Chinese.
But Institute of Policy Studies senior research fellow Yap Mui Teng warned that the reversal in the TFR's decline may be due to couples wanting to have a child in the auspicious Dragon Year.