Mainland couples who give birth to babies abroad to circumvent the family planning policy will be required to pay social maintenance fees if they bring the children back to the mainland.

"As long as they are Chinese mainland citizens and will raise the children back on the mainland, and their children are born in contravention of the policy, they have to pay the fees," said the National Population and Family Planning Commission.

In recent years, more and more well-to-do couples have gone abroad to have a second child. Some aim to give their children citizenship provided by places such as the United States, Canada and Hong Kong, while others simply want to circumvent the family planning policy, which limits most urban couples to just one child.

According to Zhai Zhenwu, dean of Renmin University's school of sociology and population, the social maintenance fees vary regionally, ranging from two to 10 times local per capita annual income.

"Violators working as civil servants or for other government-related organizations will face administrative punishments, like expulsion, in addition to the fines," Zhai said.

But there are also exceptions, he added.

Chinese student couples who give birth to babies in contravention of the policy while studying abroad are exempt from the fees and any other punishments after they come back to China.

Also, if the parents don't apply for Chinese residence permits for their children born abroad, the family planning departments may not know the child is born in contravention of the policy, Zhai said.

"In fact a Chinese residence permit doesn't matter that much for a baby's life on the mainland," said Julie Dong, a customer manager with Meibaozhijia, an agency bringing mainland women to the US to deliver children.

Instead, parents can easily apply for a travel document issued by the Chinese government for their babies born abroad, she said.

With the document, they can enroll in primary and secondary schools like other Chinese children without paying extra fees, she said. Also, the children can choose their own citizenship and nationality when they turn 18.

The only benefits they are not entitled to are attending public kindergartens and free vaccinations, she said.

"We have a constantly rising number of customers, including some famous entertainers, and many of them are having their second child in the US," she said.

Her agency now has five outlets on the mainland including Beijing and Shanghai.

A baby-delivering trip to the US costs around 150,000 yuan (US$23,400).