"The share of the working-age population (ages 15-64) will decline in China between 2010 and 2030 nearly as fast as it will in Japan, the U.S. and other wealthy nations. Switching to a two-child policy could even make things worse over the next 20 year, because more births would mean that working parents would have more dependents to care for, the economists note."
China's one-child policy has hastened such a big slowdown in China's working-age population that the country's demographic future is starting to look a lot more like that of rich nations—and that's bad news for China.
According to two Citigroup economists, Nathan Sheets and Robert A. Sockin, China's "deteriorating demographics" are likely to trim 3.25 percentage points off China's annual growth rate between 2012 and 2030, compared to its double-digit growth of past decades. While industrialized nations face similar demographic challenges, they have a deeper cushion of wealth to rely upon (witness Japan.) China needs to continue to grow rapidly if it's ever to reach the fat-and-happy stage.