China's newborns totaled 17.23 million in 2017, down by 630,000 from 2006.
According to the National Bureau of Statistics, 8.83 million babies were born as a second child in 2017, up by 1.62 million from 2016.
The proportion of babies born to families that already have one child in 2017 rose by 11 percentage points year-on-year to reach 51.2 percent, the highest since the 1980s.
He Yafu, a population expert, attributed the increase to the second-child policy implemented nationwide in January 2016.
He told Beijing News on Monday that considering many couples with the desire to give birth to a second child are now already having their second child, the number of the births of second child is expected to drop in 2018.
He also predicted that the births of first children will decrease. That is partly because of the declining population of women of childbearing age - in 2017, the number of women of childbearing age (15 years old to 49 years old) dropped by 4 million from 2016 - and partly because of the reluctance of younger generations to reproduce.