BEIJING - Without China's family planning policy, the world's seven billionth person would have been born five years ago, a leading Chinese demographers said Wednesday.

The world's population will officially reach seven billion on October 31, according to the United Nations. [Photo/Newscartoon.com.cn]

"The population of China would now be around 1.7 billion had it not been for the family planning policy," said Prof. Zhai Zhenwu, dean of Beijing-based Renmin University's School of Sociology and Population. "And the world's population would have hit seven billion in 2006."

Zhai calculated that the family planning policy in the world's most populous nation, often referred to as the "one-child policy," prevented 400 million people from being added to China's population, which is 1.34 billion at present.

His conclusion that the seven billionth person's birth was postponed by five years as a result of the Chinese policy was based on the average annual growth of the world's population of around 80 million.

China introduced its family planning policy in late 1970s in a bid to curb the large population's pressure on the environment and resources, as well as to raise the population's quality of life.

According to statistics from China's National Population and Family Planning Commission (NPFPC), the proportion of China's population in the entire world has fallen to 19 percent, at present, from 22 percent three decades ago.

In the meantime, the average education term reached nine years, and the average life expectancy jumped to 73.5 years. The decreased growth rate of population also promoted the building of a sustainable economy and society.

"China spent 30 years transforming the development pattern of its population, a process that developed countries took one century to finish," said Zhai.

However, Zhai said China is still facing a variety of challenges with its population, such as an increasing gender imbalance and aging population, among others.

Cover Story: Planet prepares for 7 billionth inhabitant