BEIJING—A Chinese claim that without its government's severe family planning limits world population would have hit the 7-billion mark years earlier is drawing fire from demographers who call it baseless and unscientific.
A report by the official Xinhua News Agency that was carried on news websites and in newspapers said China for preventing 400 million births with its one-child policy -- a set of restrictions that were launched three decades ago limiting most urban families to one child and most rural families to two.
"The population of China would now be around 1.7 billion had it not been for the family planning policy," Xinhua quoted Zhai Zhenwu, director of Renmin University's School of Sociology and Population in Beijing as saying. "And the world's population would have hit seven billion in 2006."
The estimates and the defense of the one-child policy are not new. But with the United Nations projecting that global population will hit 7 billion on Oct. 31, the milestone has refreshed debate about the global need for population control and whether China, still the world's most populous country, serves as model.
Many demographers deny that the one-child policy curbed 400 million births and say China's methods must not be copied.
"A draconian birth control policy is not the answer to the world population problem," said Cai Yong, an assistant professor at the University of North Carolina, Chapel Hill, and an expert on China's population. Cai said Zhai and the government are "rewriting China's fertility reduction history."
Cai and Wang Feng, director of Brookings-Tsinghua Center for Public Policy, last year published a paper in China Reform, a Chinese-language policy discussion magazine, debunking the 400 million figure.
They argue that between 1979 and 2009, China averted 200 million births, half the government estimate. They arrived at the number by calculating what the population would have been if China had maintained its 1979 fertility rate of 2.75 and comparing it to the 2009 fertility rate of 1.7 and population.
Zhai, the professor quoted by Xinhua, said he knows Wang and Cai's paper. Though he stands by the 400 million figure, he said it covers a period that begins a decade earlier than the one-child policy when China began encouraging later marriages and fewer children.
"It's an estimate anyway," he said. "And there are many different numbers out there but it doesn't change the basic fact that the policy prevented a really large number of births."
Behind the debate over the 400 million figure is larger campaign about whether and when the government should relax the family-planning limits. Cai and Wang argue that the policy has worsened the country's aging crisis and the imbalanced sex ratio by encouraging families with a preference for male heirs to abort baby girls.
"I think many people like to have these simple large numbers that are easy to recognize, and impressive, but unfortunately it's baseless, it's unscientific," said Wang. "The Chinese government likes to use this as a way to support, to justify the continued implementation of the one-child policy, which is long outdated."
The scholars say that China's biggest drop in fertility came from 1970-79 before the one-child policy was introduced and that the reductions since then have been largely due to economic and social reforms that make small families more attractive.
Cai said China's fertility rate, or the number of children the average woman is projected to have in her lifetime, dropped by more than half from 5.8 in 1970 to 2.7 in 1979. The one-child policy was introduced in 1978 and formally launched nationwide in 1980, and since then the fertility rate has fallen to about 1.5.
Wang notes that other countries with similar reductions in fertility rates over the last few decades, such as Thailand and Iran, saw those changes occur without imposing a one-child policy.
"Thailand and China have had almost identical fertility trajectories since the mid 1980s," he said. "Thailand does not have a one-child policy."