Half of China's 1.34 billion population live in cities and towns, according to a census on Thursday that pointed to the daunting tasks ahead for policymakers as the labour market shrinks and the nation grows older.
The census, which showed overall population growth slowing sharply in the decade to 2010, revealed fewer Chinese than some demographers had expected and could spur calls for China's tough family planning policies to be relaxed.
China remains the world's most populated country but the rise of 5.8 percent was almost half the pace recorded in the last census a decade earlier. Some experts had expected China's population to reach 1.4 billion.
"China is for the first time crossing a historical landmark from a country that's dominated by people engaging in agriculture, living in the countryside, to an urbanised society," said Wang Feng, a demographer who is director of the Brookings-Tsinghua Center for Public Policy in Beijing.
The mammoth task of counting China's population required six million workers and revealed a population that in a single decade increased by 75 million, more than the number of people in Britain.
The census showed the proportion of young Chinese shrinking as the elderly population grows. Many demographers have said China's choke on family size threatens the future of the world's fastest-growing major economy as fewer people are left to pay and care for a greying population.
The report points to pressure for wage levels to rise as the working-age population shrinks, a need for social safety nets to support a greying nation and stress on urban infrastructure as rural migrants flood to cities such as Beijing and Chongqing.
"The data from this census show that our country faces some tensions and challenges regarding population, the economy and social development," Ma Jiantang, the head of the National Bureau of Statistics, told a news conference.
The census also highlighted stark differences between China and the rival emerging economy of India, which reported its own population tally on March 31. India's population grew three times faster than China's over the past decade and is far younger.
The proportion of mainland Chinese people aged 14 or younger was 16.60 percent, a fall of 6.29 percentage points from the number in the 2000 census.
Those aged 60 or older increased to 13.26 percent of the population, up 2.93 percentage points.
Such figures could encourage the government to relax family planning restrictions that limit nearly all urban couples to one child, while rural families are usually allowed two, said Du Peng, a professor at the Population and Development Studies Center at Renmin University in Beijing.
"The total population shows the general trend towards slowed population growth and as well an older population, and in the next five years or longer that will be an important basis for population policy," said Du.
"The ageing of the population appears to be faster than was expected," he said.
Statistics chief Ma said the census vindicated the government's firm, sometimes harsh, family planning policies.
"These figures have shown the trend of excessively rapid growth of China's population has been under effective control," Ma said.
But one economist said China's slower population growth and shrinking pool of migrant labour from the countryside could add to long-term pressures driving up wages and prices.
"(Slower population growth) is starting to show in rural labour markets and the entire economy feels the pain as this becomes a major source of inflation," said Dong Tao, an economist at Credit Suisse in Hong Kong.
The Chinese government's controls on family size have brought down annual population growth to below 1 percent and the rate is projected to start falling in coming decades.
"Top leaders should listen less to a bureaucracy that was created to control population and has its own political agenda and mandate," said Wang of the Brookings Institute.
Still, President Hu Jintao said on Wednesday that China would continue to "uphold and perfect reproductive policies (to) earnestly stabilise a low birth rate," Xinhua news agency reported.
Ma did not announce any policy changes, but he hinted that the census results could lead to adjustments. China, he said, would have to "actively respond to the new challenges in demographic development."
The report showed that 49.7 percent of China's population lived in urban areas by 2010, up from 36.1 percent in 2000, although the previous census used a different counting method.