A statement about the new campaign posted Thursday on the Web site of the Shanghai Population and Family Planning Commission was quick to emphasize that it didn't signal any change in China's one-child rule and was only an attempt to let people know about the policy's many exceptions.
About 3 million, or 21 percent, of Shanghai's nearly 13.7 million registered residents are now aged 60 or older, the statement said, and providing for them poses a huge challenge for the city.
Future labor shortages and social security funding problems could be helped by boosting the young population of Shanghai, it said.
Xie Lingli, the commission's director, was quoted as saying authorities are going door to door to try to encourage couples to have a second child — if both grew up as only children.
China's family planning policy was designed to control the country's exploding population and ensure better education and health care. Though commonly known as the one-child policy because it limits most couples to having just one, there are numerous exceptions and loopholes, some of them put into practice because of widespread opposition to the limits.
Two or more children are allowed for many ethnic minorities, rural families and couples in which both parents were only children. In some cases, divorced parents may also have a second child with a new spouse and people with physical handicaps who have trouble earning an income can also have more than one child.
Critics say the policy has led to forced abortions and sterilizations as local authorities pursue birth quotas set by Beijing, plus a dangerously imbalanced sex ratio as families abort girls out of a traditional preference for male heirs.
The government says the controls have prevented an additional 400 million births in the world's most populous country of 1.3 billion.
A report issued this year by a U.S.-based group said China's current ratio of 16 elderly people per 100 workers is set to double by 2025, then double again to 61 by 2050, due partly to family planning limits.
Without a universal pension system to cover all the elderly, millions of older Chinese could fall into poverty, triggering social and political unrest, the Global Aging Initiative at the Washington-based Center for Strategic and International Studies said in the April report.
Gu Baochang, professor of demographics at People's University in Beijing, said the next step for Shanghai and other cities with low fertility rates will likely be a new rule that allows couples in which just one partner is an only child to have two children, he said.
Gu said ideally China should scrap the one-child limit altogether, but that he doesn't expect that to happen soon.
"Because China has never been an aging society, we don't know what it looks like and the burdens it will bring," Gu said. "It may take a while for society and the government to understand the change that is coming."
China's top family planning official, Zhang Weiqing, said last year that the country would not consider changing the policy for at least a decade for fear of a destabilizing population surge.