The resident population of Guangdong province ranked second in the country last year, and experts are warning it faces new challenges to sustainable development.

The population was 94.49 million, second only to Henan province, which last year was 98.69 million, according to a Guangdong provincial population and family planning conference held on Monday.

"The fourth baby boom has arrived in Guangdong," vice-governor Lei Yulan said.

The first three booms occurred at the start of the 1950s, the end of the 60s to the beginning of 70s, and the mid-80s.

Experts said the current baby boom started in 2006 and will last for about 10 years.

The number of births per year will increase by more than 1 million during the 11th Five-Year Plan (2006-10), Lei said.

It is expected that in 2010 the population will be 96 million.

As well as its resident population, Guangdong has a migrant population of about 16 million people. The province is facing tough challenges as it attempts to manage such high numbers.

Guangdong had a GDP of more than 3 trillion yuan ($429 billion) last year. But the per capita GDP is very low due to the large population.

The large population, however does have it positive side, such as easing the burden of looking after children, and elderly people, Zheng Zizhen, director of the sociology and demography research institute of Guangdong Academy of Social Sciences, said.

"But there are more negatives," Zheng said.

"The burgeoning population will result in a large number of unemployed people, and this will affect social stability," he said.

In Guangdong's rural areas, about 7 million people are unemployed, he said.

Such a large population also causes more domestic waste, Zheng said.

Employment, education, social welfare, medical care and housing will all come under heavy pressure if the province's population continues to rise, he said.

However, the population growth can be curbed if a technology-intensive economy takes root in Guangdong, Zheng said.

Editor: Yan