The Chinese government’s decision to allow a new exception to the country’s “one child” policy is unlikely to have a big impact on the birth rate but marks an important symbolic shift in one of Chinese communism’s most famous social policies, demographers said.

Xinhua, the state news agency, said on Friday that the number of couples allowed to have two children under the law would be expanded to include families where only one parent was an only child. Previously the law granted this concession to couples where both parents were only children.

China’s birth planning laws already allow so many exceptions that many demographers consider it a misnomer to call it a “one-child” policy: apart from families where both parents are only children, rural people are also allowed to bear a second child – if their first child is a girl or disabled – and ethnic minorities are allowed more children.