In one of the major policy moves during Xi's first five-year term, China announced in October 2015 that it would end of the rigorously enforced one-child policy and allow all couples to have two children from the start of last year.
Yi Fuxian, a researcher at the University of Wisconsin-Madison and a long-standing opponent of China's birth control policy, said more changes could be on the way next year.
"In my best guess, Xi will stop birth control totally at the 3rd plenary session of the 19th party congress [in late 2018]," Yi said.
Yi caused a stir in May by suggesting that China might have 90 million fewer people than the official population tally, making China the second most populous country after India.
Li said China's two-child policy had been effective in increasing the number of children born.
Citing official statistics, she said 17.86 million children were born in China in 2016, the highest total since 2000.
Addressing the media on Sunday, Li barely mentioned the subject of birth controls.
However, Social Security Minister Yin Weimin said China's pension system was under pressure as the Chinese population aged.
"In the 1990s, there were five Chinese workers for every pensioner, now the rate is 2.8 workers for each one," Yin said. "Moving forward, China's ageing problem will continue ... to pose stern challenges to the sustainability of the pension system."
The number of people in China's labour pool, defined as those aged between 16 and 60, has fallen for five years in a row to 2016, according to the National Bureau of Statistics.
- South China Morning Post