The policy started being an encouragement, but in 1980 it was made mandatory to only have one child.
The birth rate fell from 33 in 1979 to 17 in 1970.
The policy is estimated to have reduced the growth of 1.3 billion by as much of 300 million people over the first 20 years alone.
Many people in China value female infants less highly than males as they weren’t considered to be able to aid in work. This caused sex-selected abortion.
Females were aborted or died because of neglect, abandonment or even infanticide. This was seen more in rural areas.
Fertility rates fell about 1.6 births per woman.
The downsides of maintaining this policy is a shrinking labour force and an ageing population.
In 2013, the policy was relaxed and allowed couples to have 2 children.