In recent years, Shanghai authorities have been encouraging eligible couples to have a second child if both spouses are from a one-child family or if the first child has a non-inherited disease.

Even so, few couples want to have a second child.

"Our survey of young couples in the city found that many eligible couples said they wouldn't have another baby for various reasons, such as the high cost of living and career development," Huang said.

According to the population department, in 2011 about 12,000 eligible couples applied to have a second child, but less than half actually did.

This year, only 8.6 percent of Shanghai couples who are both from one-child families have given birth to a second child.

"Financial factors must be considered. The cost of living in big cities like Shanghai is very high. It will not be easy to raise two children in a family, and the quality of life will also be affected," said Huo Xiaohua, 30, mother to an 18-month-old boy.

The city is now experiencing a baby boom, which began in 2006, and is expected to continue until 2017. About 220,000 babies will be born this year, the highest number since 2000 and about 40,000 more than last year.

Despite the growing number of newborns, it still does not match the pace of the aging society.

Contact the writer at wanghongyi@chinadaily.com.cn