Two-child policy
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 is in effect in China and has previously been used in Vietnam. Although not mandated by law, in the 1970s, citizens of British Hong Kong were also highly encouraged to have two children as a limit, and it was used as part of the region's family planning strategies.
China
During the 1970s, Chinese citizens were encouraged to have only two children. 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.)