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when did china change the one child policy
The new law took effect on 1 January 2016 after it was passed in the standing committee of the National People's Congress on 27 December 2015.
What is the standing committee of the National People's Congress?
The Standing Committee of the National People's Congress exercises the legislative power of the People's Republic of China.
How many children were born in China last year?
China announced that it recorded 15.23 million births in 2018, a sharp drop of two million compared with the previous year.

Question: why did the policy need to be changed
Self-contained rewrite: why did china's one child policy need to be changed