A growing number of couples in Guangdong province, which relaxed the decades-old family planning policy in March, are asking hospitals to defrost their frozen embryos in the hopes of having a second child.

Huang Qing, a doctor from the department of reproductive medicine with the No 3 Hospital Affiliated to the Guangzhou University of Medical Science, said that in recent years more than 10,000 babies a year have been born in the province through in vitro fertilization. That number, Huang said, is likely to rise in the near future.

The hospital is one of three major hospitals that offer in vitro fertilization service in Guangzhou, capital of Guangdong province. More than 4,200 "test-tube babies" were born at the hospital in 2013.

Only couples who are infertile are allowed to use the technology to have children, according to current policies.

Huang said seven or eight couples, many of whom had their first child using in vitro fertilization, come to the hospital each day to inquire about having their frozen embryos defrosted in order to have a second child.

Twenty-two couples are ready to use their defrosted embryos at the hospital, Huang said.

Roughly 60 to 70 percent of couples who successfully conceive a child through in vitro fertilization have had additional embryos frozen at the hospital, Huang said.

A monthly fee of 110 yuan ($17) is needed to store the embryos in liquid nitrogen tanks at -173 C.

Currently, there are more than 50,000 frozen embryos at the hospital that were accumulated over the past two decades.

"Fortunately, we did not discard them. They can be of big use now," she said.

One of the 22 couples has had their frozen embryos at the hospital for six years, she said.

Liu Jianqiao, director of the hospital's department of reproductive medicine, said the in vitro fertilization technology has been fully developed and has a success rate of 50 to 55 percent. The service cost 20,000 to 30,000 yuan.

Liu said factors such as the delay of marriage and child rearing, increased work pressures, serious environmental pollution and the spread of sexually transmitted diseases, have all contributed to a higher frequency of infertility in China.

zhengcaixiong@chinadaily.com.cn