<P> A two - child policy is a government - imposed limit of two children allowed per family or the payment of government subsidies only to the first two children . It has previously been used in Vietnam . In British Hong Kong in the 1970s, citizens were also highly encouraged to have two children as a limit (although it was not mandated by law), and it was used as part of the region's family planning strategies . Since 2015, it has been implemented in China . </P> <P> During the 1970s, Chinese citizens were encouraged to have only one child . The ongoing Cultural Revolution and the strain it placed on the nation were large factors . During this time, the birth rate dropped from nearly 6 children per woman to just under 3 . (The colloquial term "births per woman" is usually formalized as the Total Fertility Rate (TFR), a technical term in demographic analysis meaning the average number of children that would be born to a woman over her lifetime if she were to experience the exact current age - specific fertility rates through her lifetime .) </P>

When did china's 2 child policy start