China is to relax its policy of restricting most couples to having only a single child.
The Xinhua news agency said families will be allowed two children if one parent is an only child.
The new rules will ease family planning restrictions in major cities, where they are much tighter than in rural areas.
China introduced the one-child policy at the end of the 1970s to curb rapid population growth.
But correspondents say the policy has become increasingly unpopular. By 2050, more than a quarter of the population will be over 65.
Some exceptions already exist. In some cities, both parents must be only children in order to be allowed to have a second child.
In the countryside, families are allowed to have two children if the first is a girl.
The BBC reports a traditional preference for boys has also created a gender imbalance. By the end of the decade, demographers say China will have 24 million "leftover men" who will not be able to find a wife.
Other reforms announced on Friday include a reduction in the number of crimes subject to the death penalty and the abolition of "re-education through labour" camps.
A network of camps was created half a century ago. Police panels have the power to sentence offenders to years in camps without trial.