China is on the horns of a dilemma: With the official population at 1.3 billion as of yesterday, the authorities will be congratulating themselves on a successful birth-control policy, for the total is 300 million fewer than it might otherwise have been.
But falling birth rates bring problems in their train -- an ageing population. China faces the pressing question of how to provide for its millions of pensioners.
Relying solely on a perpetually high economic growth is an illusion, most experts believe, as the country is ageing faster than it is getting richer.
Today around 10 percent of all Chinese are older than 60, but by 2030 it will be 25 percent, and by 2050 around one-third of all Chinese will be of pensionable age.
"Providing for the aged requires solutions to many problems," said Liu Hongyuan of the Research Centre for Population and Development in Beijing.
"The social safety net for the aged simply does not function properly -- it's better in the cities, but in the countryside it's a huge problem," Liu says.
Whereas today three workers support a single pensioner, within two decades this will drop to two.
An additional problem is that at least two-thirds of all workers are not members of a formal pension system, according to a recent study.
"The peasant farmers simply don't trust the pensions system," Liu says.
What goes into the pension funds gets paid out immediately and is not saved for the future.
Where under the communist system the state and the work units were responsible for pensions, this old system is disappearing with the emergence of China's "socialist market economy," without anything being set up to replace it.
Only the family remains as a social safety net.
But despite the problems, the government shows no inclination to change the one-child policy introduced in 1979, because China's resources remain limited.
For example, there is already a critical shortage of water, and the country has only 7 percent of the world's utilizable agricultural land, while home to 22 percent of the world's population.
The one-child policy is in any case only partially observed. In the countryside, where some 70 percent of the population live, two-child families are the rule. When the first child is a girl, peasant farmers are allowed to try again to secure the sought-after male heir.
Ethnic minorities, who form around 8 percent of the population, are allowed to have two or more children.
In the cities, two children are allowed when the parents themselves come from one-child families, and those wealthy enough simply pay the fines for having larger families than the law allows.
China's population is therefore growing at a rate of 10 million a year. It is estimated that the peak will be reached in 2050, when China's population will top 1.6 billion -- not enough to pay the pensions, but far too many for the jobs market.
"Another huge problem is the imbalance between men and women," Liu says.
Traditionally, male heirs are seen as providing for a secure old age, but modern ante-natal techniques like ultra-sound scans mean that female fetuses are aborted.
The result is that for every 100 girls born there are 120 boys, and in 10 years there could be a shortage of between 40 and 60 million women. Population experts warn of social problems generated by dissatisfied bachelors, increasing prostitution, increased trafficking in women and crime in general caused by men moving through the countryside unable to start their own families.