China's family planning policy has proved to be efficient for population control and the nation's development, despite concerns over gender imbalance and an aging population as a result of the 30-year-old program, demographers said Saturday.

On September 25, 1980, the Communist Party of China (CPC) Central Committee issued an open letter calling for CPC and Communist Youth League members to have only one child in a bid to keep the population below 1.2 billion by the end of the 20th century and to improve people's livelihoods.

According to official statistics, the Chinese population reached 1.33 billion by the end of last year. If the birth rate had remained at 1970s levels, the population would have reached 1.7 billion.

Three decades since the policy was implemented, 400 million births have been prevented, contributing to an 8.6 percent increase in China's per capita GDP.

Earlier this week, Vice Premier Li Keqiang said China would stick to its national family planning policy and advance the balanced development of its population in the long term.

A smaller population also means more educational opportunities. Statistics show that, up to age 15, people receive an average of 8.5 years of schooling, above average for developing countries, while the number of people in poverty has been reduced from 250 million to 40 million.

However, Wu Yaowu, a senior researcher specializing in population economics at the Chinese Academy of Social Sciences, told the Global Times that the population decline may slow down the country's GDP growth in the future.

"Population is a kind of capital. With an insufficient workforce, economic growth will slow down," Wu said.

Yao Yuan, a professor specializing in demographics and the aging society at Renmin University, told the Global Times that a society aging sooner than expected and the imbalance in gender are two major problems caused by the family planning policy.