From Science:
The policy shift may have a “modest effect in the short term” on the birth rate, says Wang Feng, a demographer at the University of California, Irvine. But its long-term impact on population trends like aging will be “mostly unnoticeable,” he predicts.

For the full story, please visit http://news.sciencemag.org/asiapacific/2015/10/researchers-react-china-s-two-child-policy-move.