Did China's one-child policy actually reduce population growth?S

China made huge headlines late last month when it decided to ease its famous "one-child policy" after more than three decades. The policy, requring most couples to have only one child, stands as one of the most famous social experiments of the past century. But how successful was it?

Top image: Adrian Zwegers/Flickr.

A lot of the discussions of China's one-child policy seem to revolve around the idea that it was a human rights violation that led to sex-specific abortions and other abuses, along with problems like a lopsided gender ratio and an aging population — but that it also had a dramatic impact, massively slowing China's population growth.

But a rising group of demographers and sociologists is disputing that idea. By taking a closer look at population figures before and after the policy took effect, and by doing a more careful statistical analysis, researchers have found that China's population growth rate would have decreased in any case, and the policy was not just cruel, but unnecessary.

Bottom line: China says the policy reduced births by 400 million since 1970 — but some experts say the number may be closer to 100 million.

What was the stated goal of China's one-child policy?

The original goal of the policy was to keep China's population to 1.2 billion in the year 2000, according to Cai Yong, a sociology professor at University of North Carolina, and a fellow at the Carolina Population Center. In fact, China's population reached a level of 1.26 billion in 2000, meaning they were over the mark by 60 million people.

Did China's one-child policy actually reduce population growth?

But the underlying motivation for that goal of 1.2 billion people was to increase GDP per capita — and China's GDP grew much more quickly than the pessimistic predictions in 1980 had expected. So the GDP per capita was way above target, even though the population also grew more quickly than intended.

What would China's population growth have been without the policy?

This is the biggest question, when it comes to judging the effectiveness of the one-child policy. We can't know what would would have happened if things had been different, because you can't prove a counterfactual.

But Cai has studied the fertility rates of 16 comparable countries, all of which saw rapid declines since 1980 without any one-child policy in place. In a 2012 paper, co-authored with Wang Feng and Gu Baocheng, Cai found that China's projections of future birth rates at the time were unrealistic, when you compare them with the experiences of other countries. Here's the table that shows his results:

Did China's one-child policy actually reduce population growth?

Talking to io9, Cai notes that Chinese Americans typically have a fertility rate of 1.5 children per women, similar to China in 2010. Japan's fertility rate has been way below that, around 1.3 children per woman, for the past 30 years. "There's no one-child policy in Taiwan, and Taiwan's fertility rate is barely above one [child per woman]," Cai tells io9. "It dropped below one in 2010."

Taiwan may be 15-20 years ahead of China in terms of economic development, but its fertility rate has been low for years, Cai adds.

Cai and his colleagues also did a Bayesian analysis of China's birth rate from 1970 to 1980 and tried to project what the trend would have been from 1980 onwards, if nothing else had changed. And they found a decline similar to the one observed in other countries.

So it seems likely that China could have reached a level of 1.5 children per women by 2010 regardless — but the decline might have been less steep.

China's population growth rate was already declining sharply

The ultra-pessimistic projections for China's population growth after 1980 are based on a strict linear progression, following China's growth rate prior to 1970.

But in fact, China's fertility rate had already fallen from 5.8 births per woman in 1970 to 2.8 births per woman in 1980, meaning it more or less halved before the one-child policy took effect.

Did China's one-child policy actually reduce population growth?

So claiming that the one-child policy caused fertility declines that actually happened in the 1970s is "like Obama taking credit for economic growth during the Clinton years," says Mara Hvistendahl, a contributing editor for Science and author of Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of Men.

In the 1970s, the Chinese government was experimenting with less authoritarian approaches to population control, including the "Later Longer Fewer" policy, which encouraged women to wait longer to have children and have fewer of them. "Compared to the brutal one-child policy, it's more benign," says Cai.

Many women welcomed the ability to wait longer to have children, given the terrible economic situation of the early 1970s, and the government made it easier to access birth control. The government also had study sessions and meetings to push the idea of having fewer children.

But the government was already trying coercive policies in the 1970s, Hvistendahl tells io9:

Less stringent birth limits were introduced in the early 1970s. And there are signs that forced abortions, etc. were occurring at that time. Teams of medics and midwives moved through the Chinese countryside carrying out "shock attacks" during which they performed IUD insertions, sterilizations, and abortions on women and sterilized men. Some of this made it into the Western press as early as 1973.

What you believe China's population would be today depends on your assumptions about whether the birth rate in China would have continued to fall with or without the policy, says Therese Hesketh, a professor with the Institute for Global Health at University College London.

For her part, Hesketh believes the estimate of 100 million births prevented by the one-child policy is probably on the low end, and the real answer is somewhere between 100 million and 400 million.

What was the compliance rate with the one-child policy?

The policy was implemented differently in different regions, and there were a ton of loopholes, depending on where you lived. In some places, you could have more than one child if you were a fisherman. In others, you could have more than one child if your first child was a girl, says Hvistendahl.

Did China's one-child policy actually reduce population growth?S

Around the 25th anniversary of the policy, demographer Wang Feng set out to figure out how many couples were actually restricted to one child, adds Hvistendahl. The answer was pretty high: 63 percent. "For most Chinese couples, the one-child policy is a very real thing."

The 1960s and 1970s saw a huge population panic

The United Nations held a huge conference on population control in 1974, at which the Chinese denounced Western calls for population control as part of an imperialist agenda, and the Indian delegate argued that "development is the best contraceptive."

And yet, both China and India were deeply concerned about controlling their population growth in the mid-1970s. China tried several other programs before the one-child policy.

And India sterilized 8.3 million people (mostly men) in "sterilization camps" between 1975 and 1976 — a program which was so unpopular, it helped bring down the government of Indira Gandhi. The United States also has a long history of forced sterilizations.

The number of births is not the same as the rate of population growth.

This is an important point that often gets lost in the discussion of how many births were prevented by the one-child policy, says Cai. It's not just how many babies are born, but when women become mothers, and how much their babies are spaced apart.

"If every woman has a child at age 20, that means in 100 years there will be five generations," says Cai. "But if we delay that to age 25, in 100 years there will be just four generations. That will have a significant effect on the country's population."

So it's "a little simplistic to say the number of births is equal to the number of people," Cai adds.

Do Chinese people actually want more than one child?

That's sort of the biggest question — the birth rates fell in those other countries not because of government coercion, but because a lot of families were happy with just one child.

Did China's one-child policy actually reduce population growth?S

Cai did another research paper in which he surveyed 30,000 women in Jiangsu Province, a third of whom who were eligible to have a second child. But only a third of those eligible women said they would consider having a second child. And when Cai returned to the province, he found that only 4 percent of eligible women had had a second child, a low figure that shocked him.

Cai believes that many people in China now want only one child so that they can give their kids access to the best education and economic opportunities. Ten years ago, one in 20 college-age people in China attended college, and now it's up to about one in three.

Adds Hvistendahl, "Perhaps the largest success of the policy, if you can call it that, is that it really turned China into a one-child [country]. Many people just don't want more than one child now."

But Hesketh says it's an "extreme view" to say that most people in China don't actually want a second child at this point. "I know many people in China with one child who would have liked to have had two," she says. Hesketh herself has two children, and when she's taken them both to China, people would come up to her on the street and say, "You're so lucky to have two." It's "almost universal" to hear people say that.

Hesketh also frequently hears Chinese people say that their child is lonely because he or she is an only child.

What will the long term effects of this policy be?

It's much easier to reduce the fertility rate than to increase it, Cai stresses in his paper with Wang and Gu. So the growth rate of China's population will probably continue to go down — and Cai expects to see the population actually shrink.

Did China's one-child policy actually reduce population growth?S

"If you count the so-called ripple effect and echo effect, it could be endless," Cai tells io9. Within 200 or 300 years, the population of China could "diminish very dramatically," with the population being cut in half if current trends continue. Usually, population experts consider 2.1 births per woman the minimum amount needed to maintain a stable population size, so China's rate of 1.5 per woman is one-third below "replacement level." This means every generation is smaller than the last, and the number goes down exponentially.

Thus, even if the one-child policy has had a less dramatic effect than the Chinese government likes to claim, it could have a huge effect in the next century.

A general population decline, around the world, might not be a bad thing, since "we have enough people to go around," says Cai — but if the trend continues too long, "that's a different story."

Then there's the rapidly aging population. Some sources say a quarter of China's population will be over 65 by 2050, but Cai believes it could be as high as 30 percent.

Hesketh also sees China suffering economically as its labor force shrinks due to the lingering effects of the policy. "They couldn't have predicted they would need a huge labor [supply] of young men" to work in factories, she notes. "China could lose its competitive edge because of the lack of young people."

Did China's one-child policy actually reduce population growth?S

And of course, there's the oft-noted problem of the massive population of young men who won't be able to find wives due to the gender imbalance created by widespread abortions of female fetuses.

Bottom line: How will history judge the one-child policy?

"The one-child policy shows that you can't push population control methods on people without expecting some sort of horrible side effects," Hvistendahl tells io9. "I would call them unintended consequences except that people knew as early as the 1960s that coercive population policies would mean fewer girls born. People in China knew it as well — I found a writeup of a 1970s experiment that suggested doctors in China were looking into sex selection as a population control method."

The paper by Cai, Gu and Wang is pretty blunt in putting the one-child policy in the same category as the Cultural Revolution and the Great Leap Forward, two other terrible hardships imposed by the state:

History will remember China's one-child policy as the most extreme example of state intervention in human reproduction in the modern era. History will also likely view this policy as a very costly blunder, born of the legacy of a political system that planned population numbers in the same way that it planned the production of goods. it showcases the impact of a policymaking process that, in the absence of public deliberations, transparency, debate, and accountability, can do permanent harm to the members of a society.

All images by Associated Press, except top image.