The Chinese Communist Party announced that it will allow couples to have two children instead of limiting them to just one. The decision comes as many worry about China's aging population and shrinking workforce. (Jenny Starrs/The Washington Post)

China said Thursday that it will abandon its controversial “one-child” policy and allow all couples to have two children, effectively ending the biggest ­population-control experiment in history amid growing pressure from a rapidly aging population.

The move, which came after a meeting of the Communist Party leadership, reflected concerns about potential labor shortages and rising numbers of elderly people that would greatly strain the economy in the years ahead.

The communique from a plenary session of the party’s Central Committee did not say when the policy change will be implemented, only that the party had decided to “fully adopt the policy that one couple is allowed two children [and] actively take action on aging population.”

China’s unpopular one-child rule was introduced in 1980 and was brutally enforced through huge fines, forced sterilizations and abortions, experts say. It empowered and enriched a huge swath of officials, with bribes often paid to skirt the rules.

It also skewed China’s sex ratio as a result of the selective abortion of girls, who are much less favored in traditional Chinese culture.

Calls to abandon the policy have crescendoed in the past decade, but the Communist Party moved slowly, partly relaxing the rule in 2013 before Thursday’s announcement.

Experts on Chinese affairs, including Wang Feng at the University of California at Irvine, have long warned that the country was heading toward a “demographic precipice” that could challenge the legitimacy of Communist Party rule.

Wang called the policy’s abandonment “great news” even if the effects will take a generation or longer to filter through.

“This really marks a historic point to end one of the most controversial and costly policies in human history,” he said. “But China for decades to come will have to live with the aftermath of this costly policy.”

The nation’s fertility rate — estimates range from 1.4 children per woman to 1.7 — is far below that of the United States and many other nations in the developed world, leading to a rapidly graying society and increasing demands on the state, such as social programs and health care for the elderly.

It also means a substantial decline in the supply of young labor to power the world’s No. 2 economy as it seeks to dethrone the United States.

China’s working-age population fell for a third straight year in 2014, declining by 3.7 million to 916 million, according to government data, in a trend that is expected to accelerate.

Meanwhile, the number of people 60 or older will approach 400 million, or a quarter of the population, in the early 2030s, according to U.N. forecasts. The 60-plus age group represents about a seventh of China’s population.

“The reform will slightly slow down China’s aging society, but it won’t reverse it,” said Peng Xizhe, a population professor at Fudan University. “It will ease the labor shortage in the long term, but in the short term it may increase the shortage because more women might stop work to give birth.”

The policy was introduced in delayed reaction to booming birthrates as China recovered from Mao Zedong’s disastrous Great Leap Forward and the famine of 1958 to 1962. But by 1980, it actually was no longer needed, many experts argue. Birthrates in China already had declined sharply during the 1970s.

Wang said the one-child policy was “a textbook example of bad science combined with bad politics” that was morally questionable and primed a demographic time bomb by driving down fertility rates further.

Despite the demographic pressure, Thursday’s communique said China was “sticking to the basic policy of state family planning” and “population growth strategy.” In other words, it is not taking its hands off the rudder entirely: Under the new policy, couples will still be limited to two children.

“That’s mostly political face-saving,” said Wang, asserting that rulers throughout Chinese history were unwilling to admit that “we made a mistake.”

The policy was eased in 2013 to allow couples to have a second child if either parent was an only child. Rural couples already could have a second child if their first child was a girl.

Members of some ethnic minorities, including Tibetans, were exempt from the restrictions.

The policy shift two years ago, however, did not appear to lead to a big boost in birthrates, with economic pressures and the cultural norms around having one child meaning that many families decided to stay as they were.

“The change won’t cause a baby wave, as the last policy change proved,” Peng said. “Couples chose not to have a second child because of economic pressure and insufficient social welfare.”

Another population expert, who was involved in policy formation and spoke on the condition of anonymity because she was not authorized to give her name, said the change will not have significant economic effects. “Its political meaning is much greater than its demographic meaning,” the expert said. “Academics have continuously lobbied the government to abandon birth control for around 10 years. The good thing is the government is correcting the direction” of policy.

Future population growth may depend partly on whether the government introduces policies to encourage childbirth, such as longer maternity and paternity leave, Peng said.

Already there are signs that other changes are under consideration. Li Bin, the head of China’s National Health and Family Planning Commission, told state television that the authorities should improve the supply of public services, including reproductive health care for women, and the availability of kindergartens and nurseries.

Reaction on social media was enthusiastic. “I can’t even believe this is real,” one user posted on the Weibo microblogging service. Another posted: “At least people have an option. Good.”

There was also humor, and some bitterness. “Finally, don’t have to go to the U.S. to have a second child,” one user posted.

“Can we have the fines back? And can we get rid of that certain department?” another wrote.

“I don’t even want this one,” another user joked, while another observed, “But I fear I won’t be able to raise them,” in a reference to the cost of bringing up two children.

The communique from the Fifth Plenum also reflected China’s growing concern about climate change, saying the country will “actively participate in global climate change negotiations.”

Investors took notice. Shares of companies with infant products — including baby-formula makers Mead Johnson, Nestle and Danone — saw share prices jump in anticipation of potentially greater sales in China.

Xu Yangjingjing and Xu Jing contributed to this report.

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