HONG KONG » The Chinese government’s decision to partly relax a decades-old one-child limit on couples has already encountered two problems likely to test dozens of social and economic changes promised by President Xi Jinping – vagaries about implementation and magnified public expectations of even bigger changes ahead.

The limited curtailing of rules that restrict most city-dwelling couples to raising just one child was a highlight of 60 proposed reforms endorsed by a Communist Party Central Committee, which were released to the public Friday. The change will allow couples to have two children if either the husband or wife is an only child. Couples can now have two children only if each of the spouses is an only child. Most rural families are already allowed to have two children.

The Chinese state-run news media have celebrated the shift as demonstrating that Xi’s government is willing to make changes that have been debated, and delayed, for many years. But over the weekend, a senior official in the National Health and Family Planning Commission said that provincial-level governments would decide when to carry out the new policy, and he stressed that the government had no plans to further relax family size restrictions.

"There will not be a uniform nationwide timetable for starting implementation," Wang Pei’an, a vice minister of the commission, said in a question-and-answer transcript issued by Xinhua, the state-run news agency. "But it would be inadvisable for the lag in timing of implementation between each area to be too long."

Provincial-level governments include large municipalities, like Beijing and Shanghai, which answer directly to the central government.

Wang Feng, a demographer who teaches at the University of California, Irvine, and Fudan University in Shanghai, has estimated that the policy change could lead to 1 million to 2 million extra births in China every year, on top of the 15 million or so births a year now. But that limited change has raised hopes among experts and citizens that the government could let all couples have two children, and eventually even scrap state limits on family size.

"Two children should be the standard," Zhang Yuan, a civil servant in Nanjing, a city in Jiangsu province, eastern China, said in a telephone interview. She said she was already eligible to have two children, as both she and her husband were singletons.

"Even if the policy was further relaxed, it’s not necessarily so that every couple will have more kids," she said. "It’s a huge pressure to raise a kid, especially in China."

But, she said, she and her husband were thinking about having a second child in two or three years, in addition to their 2-year-old daughter. "I’m not very concerned about the financial pressure. Rich or not, you can raise the kids either way."

Wang, the health commission official, emphatically said no to ideas of a further relaxation of the general one-child rule.

"Adjusting and improving family-planning policy is not tantamount to relaxing that policy," he said. Allowing all urban couples to have two children would create too many burdens for society, he said.

"There would be a quite serious concentration of births that would impose very heavy pressure on basic public services," he said. "In the longer term, that would create a cyclical surge in births, so the total population would experience sustained growth, and the arrival of the population peak would be delayed."

The relaxation was possible because of China’s slowed population growth, and in the longer term it will help to offset the pressures of coping with an aging society, Wang said. But the policy change will not significantly alter China from its course toward an increasingly old society with a slowly shrinking labor force, said Hua Sheng, an economist at Southeast University in Nanjing.

"There’s unlikely to be a major short-term impact," Hua said. "The economic impact also will depend on how much actual behavior changes. But the real significance is that it’s a positive signal – the first major change in family planning after many years."

The party Central Committee meeting that endorsed the change in family policy also vowed to abolish re-education through labor, a form of punishment that can be used to imprison people for up to four years without any real judicial scrutiny or chance to appeal. But that proposal, as well as a slew of economic changes promised by the committee, also await detailed rules for implementation.

For eligible couples, the question of whether to have a second child will come down to choosing between the pleasure and benefits of another child against the pressures in a society where health care, schooling and housing costs can be daunting even for prosperous members of the middle class.

Li Xuebing, a real estate advertising salesman in Beijing, said he and his wife would be eligible to have another child under the new policy, in addition to their 18-month-old son.

"Ever since the first, we’ve wanted to have a second child," he said.

"I’m an only child, and my experience growing up was that an only child carries too many burdens from the family’s expectations," he said. "I think this policy opening will grow bigger and bigger."