Since new family planning laws were enacted in the city one year ago, 4,413 local couples have delivered a second child, 1.7 times the number reported during the previous year.
The new rules offer more couples the chance to have a second child and do away with a mandatory four-year waiting period between children.
Most of the rapid increase can be credited to couples that both come from one-child families, who are now allowed to have a second child without paying any penalty.
Another group responsible for the increase is couples where one spouse is an only child and the other is a farmer.
In 2003, only 131 such couples delivered a second child, while the number rose to 442 last year, officials said.
"The proportion of second children from such families rose from the previous 5.05 percent to 10.02 percent," said Xie Lingli, director of the Shanghai Population and Family Planning Commission.
The number of families with a first child who had a non-inherited disease that had a second child dropped 2 percent last year, compared with 2003.
In addition to carrying out the amended rule, local population authorities also took various measures to enhance the city's population structure, improve the health of newborns and give support to rural families that follow the family planning policy.