China formally eases one-child policy for parents who didn't have a sibling Law passed in 1980 to help manage the country's increasing population Extra two million babies could be born every year as a result of rule change Under old rules fines imposed for any couple that has more than one child China has formally allowed couples to have a second child if one parent is an only child. The rule-change is the first major easing of the three-decade-old restrictive birth policy which has been criticised by human rights campaigners First announced by the ruling Communist Party's leadership in November, the decision was officially sanctioned by the standing committee of China's top legislature, the National People's Congress. China has formally eased its one child policy, meaning that any couple where one of them is an only child can have two children Implemented in 1980, China's birth policy has limited most couples to only one child. The one child police was introduced in China in 1980 to help manage the country's huge population However, a second child was permitted if neither parent has siblings or if the first born to a rural couple is a girl. Any couple who broke the rules by having more than one baby faced a fine, but familes that found themselves expecting twins were exempt. The one child policy was brought in to limit the growth of the world's most populous country, which has 1.35 billon inhabitants. Experts have estimated the easing would benefit some 15 million to 20 million Chinese parents - mostly in cities - and result in 1 million to 2 million extra births per year. This is on top of the 16 million babies born annually in China. It is claimed that the extra births are unlikely to strain resources such as the health care and education. China has credited the restrictive policy with managing its population growth and improving the economy. However, critics say the rules are a violation of human rights. The rule-change is the first major easing of the three-decade-old restrictive birth policy