China's top family planning authority stressed that its local affiliates must implement the current one-child policy until a new policy allowing all couples to have two children goes into effect after being ratified by legislators.

Local authorities in each province should not carry out the two-child policy "willfully," the National Health and Family Planning Commission (NHFPC) said on Sunday, refuting claims by one official in Central China's Hunan Province that the new policy went into effect as soon as it was announced.

"Those pregnant with a second child will not be punished as of today," Zhan Ming, deputy director of the Provincial Health and Family Planning Commission in Hunan Province, was quoted as saying by Hunan Daily on Friday.

The Communist Party of China (CPC) announced the abolition of its one-child policy at the close of the Fifth Plenary Session of the 18th CPC Central Committee on Thursday. The change aims to rebalance the country's population development and offset the burden of an aging population.

According to a communiqué released after the plenum, a final plan for the policy change will be ratified by the annual session of China's top legislature in March.

The NHFPC estimates that about 90 million families may qualify for the new two-child policy, which could help raise the population to an estimated 1.45 billion by 2030.

China, the world's most populous country, had 1.37 billion people at the end of 2014.