China’s Communist Party on Thursday officially ended its policy that limited most families to a single child, an acknowledgment that the 1970s population-control measure was outdated, was holding back economic growth and had distorted China’s demographics in ways that could hurt the party’s long-term hold on power.

Some experts were surprised by the suddenness of the decision, even though the problems caused by the one-child policy have been apparent for many years. With so many families limited to a single child, China’s labor force is shrinking and working people without siblings are struggling to care for their aging parents.

Moreover, the policy has contributed to a surplus of men, partly because of a patriarchal tradition of favoring male children. That means an excess of young males with no marriage prospects – a formula for potential unrest and chaos of the kind party leaders fear most.

“Certainly the Communist Party for many years said that the sex-ratio imbalance is a severe societal problem,” said Leta Hong Fincher, a Hong Kong-based sociologist who specializes in Chinese policy toward women and families. “They have been talking about loosening the policy for years. Still, I am surprised they did this without a more gradual step. It suggests they felt they needed to move rapidly because of the demographic crisis.”

Even with the lifting of the one-child rule, the Communist Party hasn’t completely gotten out of the business of dictating reproductive decisions. Under the new policy, announced in a party communique late Thursday, couples nationwide will be allowed to have two children, but no more.

It also appears the party will not immediately loosen restrictions on single women having children, a sore point for the country’s feminists.

China introduced its one-child policy in 1978, two years after the death of Mao Zedong, who throughout his rule had encouraged large families. By the late 1970s, the party was growing increasingly concerned about the population’s strain on resources. The program went into effect two years after it was announced.

Experts are divided on how effective the one-child rule has been stabilizing China’s population of nearly 1.4 billion. The policy was unevenly enforced, with exemptions and lose oversight for ethnic minorities and rural farmers.

Even so, implementation of the policy created hardships and heartbreaks for many. Government regularly fined and ostracized families breaking the rules. In one of its most controversial aspects, local officials forced an uncounted number of women to undergo abortions, often late in pregnancy.

Because of cultural pressures to create male heirs, many families gave up their daughters for adoption – filling Chinese orphanages with female toddlers and fueling what became a generation of China-born adoptees in the United States and elsewhere.

Because of such policies and practices, China today has a gender imbalance that, in terms of scale, is approached only by that of India. According to a report by China’s National Population and Family Planning Commission, there will be 30 million more men than women nationwide within five years.

In her book, “Leftover Women,” Hong Fincher chronicles the Chinese government’s clumsy efforts to cope with this imbalance. One major focus, through state media, has been to put pressure on women to marry and rear children in their mid-20s.

“Restless young men are seen as a threat to the foundation of Chinese society,” she wrote. “And single women threaten the moral fabric as well, for being free agents, unnatural in failing to perform their duty to give birth and tame a restless man.”

Now that China is abandoning the one-child rule, Hong Fincher expects there will be another round of propaganda, pressing married couples to take advantage of the new policy and rear a pair of children.

With or without effective messaging, it is unclear if the policy will have its intended effect.

In 2013, China relaxed the one-child rule, allowing families to have a second child if one parent was an only child. The National Health and Family Planning Commission estimated that the relaxed rule would prompt 11 million more couples to have a second child. But by the beginning of this year, fewer than 1.1 million had sought out the required permit.

Experts say China’s increasingly affluent population is having fewer children for the same reasons as their counterparts worldwide: Urban housing costs are expensive, women want to launch their careers before having children and some don’t want to have children, regardless of circumstances.

“Increasing the child quota is unlikely to work in re-balancing China’s aging population, because China, like everywhere else, is looking at a low birth rate especially among affluent, well-educated women,” said Dr. Anna Smajdor, a medical ethicist at the University of East Anglia in England.

“In many cases, it is not that women are not allowed to have more children, but that they do not want to.”

It is also unlikely the new policy will significantly recharge China’s labor force, the source of its economic expansion since the 1990s.

According to China’s National Bureau of Statistics, the nation’s working-age population decreased by 3.7 million between 2013 and 2014. While the working-age population still tops more than 900 million, those numbers are expected to steadily decline, while societal costs of caring for the elderly increase.

“You add up all these societal challenges, and it is hard to predict what will happen,” said Hong Fincher. “Yes, finally the government has done it. It has gotten rid of the one-child policy. But it will take decades to reverse the negative trends.”