Chinese parents say their only children are often spoiled 'little emperors'
The authorities in China say they have found that most Chinese women would like to have more than one child.
Family-planning officials say their research indicates that 70% of women want to have two babies or more.
Couples who ignore China's birth control policies usually pay fines and may face discrimination at work.
The authorities say the policy, which will not be relaxed, has prevented hundreds of millions of births and has helped to make people wealthier.
The research was conducted in 2006 but has only been released now.
China has the world's biggest population, of more than 1.3 billion people.
It has restricted many families to one child since the late 1970s, though in most rural areas couples are allowed a second child if their first is a girl. Different birth-control policies also apply to some ethnic-minority groups.
As in other countries, for many Chinese women economic constraints may play a role in limiting the size of their families.
The China Daily reported the survey results, which showed parents would like a son and a daughter, at least.
"Our research shows that 70.7% of women would like to have two or more babies," the China Daily quoted Jiang Fan, vice-minister of the National Family Planning Commission, as saying.
Most women, or 83%, want a son and a daughter, the survey said.
"Some mothers think only-children suffer from loneliness and can become spoiled," the minister was quoted as saying.
Magazine editor Lin Ying, 26, told the newspaper she wanted to have two children in the next five years.
"Only children often grow up to be self-centred," she was quoted as saying.
The many only children of China have earned the nickname of "little emperors" for the love and treats lavished upon them.
Despite the survey results, the commission said China would achieve its goal to keep its population within 1.36 billion by the end of next year.
"China's family planning policy underpins the country's economy and demographics," Li Bin, minister of the commission, was quoted as saying.
China's birth-control policies have been hugely controversial at home and abroad, as enforcement has involved forced abortions and other abuses.
It has also been blamed for a gender imbalance, as a traditional preference for boys has persuaded some parents to abort girl foetuses.