China's one-child policy has prevented almost half a billion births but has turned into a demographic time bomb as the population ages, storing up huge economic and social problems for the country.
As the world's population hits the seven billion mark, straining the earth's resources, China can claim to have curbed its birth rate to around 1.5 children per woman since the policy was introduced in 1979.
Without the birth limits, which no other country applies as rigorously or on such a scale, the world's most populous nation would have hundreds of millions more mouths to feed than the 1.34 billion it has now.
But from modern cities to remote villages, its implementation has involved abuses from mass sterilisation to abortions as late as eight months into the pregnancy. Baby girls have also been abandoned and killed.
Couples who defy the rule can face fines amounting to several years' salary, have access to social services cut and even go to prison. Their so-called "black children" have no legal status in China.
Ethnic minorities and farmers whose first child is a girl are exempt from the restriction and in some areas, couples where both parents are only children are also allowed to have a second baby.
But three decades on, demographers, sociologists and economists are warning of a looming crisis as China becomes the only developing country in the world to face growing old before it grows rich.
China's crisis is approaching "incomparably faster" than in Europe, where fertility has fallen very gradually over the last century, Paris-based demographer Christophe Guilmoto told AFP.
In the next five years the number of people in China over 60 will jump from 178 million to 221 million -- 13.3 percent to 16 percent of the population -- according to the People's Daily Online
By 2050, a quarter of China's population will be over 65, the Commission for Population and Family Planning said, compared to just nine percent today.
Already, half of China's over-60s live alone, a situation unthinkable before, when four generations would live under one roof.
The upside-down pyramid -- whereby a single child shoulders responsibility for two parents and four grandparents -- is a major headache for the government, particularly as unemployment rises, forcing more and more people to migrate to cities for work.
Liang Zhongtang, a demographer involved in family planning, said the pressure would grow as Chinese born between 1962 and 1972 retire.
"Nearly 30 million babies were born each year during that period, compared to six or seven million each year right now, you can imagine how big the burden on the government will be," he said.
China already lacks medical facilities for the elderly, retirement homes and qualified health care workers. The government plans to double the number of beds in specialised institutions to six million by 2015, but that only covers the existing shortfall.
China has barely begun to put in place a universal social security and retirement system, and over two-thirds of the rural population does not have a pension.
So, should China end, or at least relax its one-child rule?
"Of course!" said He Yafu, a Chinese demographer. "The reproductive right is a human right, whether and how many children a couple want to have has nothing to do with the government.
"Even if China relaxes the one-child policy, I believe there won't be many couples wanting too many children", He told AFP, as middle-class couples around the world opt increasingly for smaller families.
Guilmoto is hopeful that fertility might rise in the future, even if "this is very uncertain when we look at the most advanced regions where it comes close to one child per woman".
Women are increasingly deciding against having children at all, opting instead to pursue careers and enjoy their growing material wealth.
But the southern province of Guangdong -- the engine of China's economy with its 104 million residents -- this month decided against relaxing the policy.
China's most populous province ruled there would be "no major adjustments" to the policy in the next five years, said Zhang Feng, head of the Population and Family Planning Commission.