Wang Yuan, a teacher in a township kindergarten in Xuzhou, Jiangsu province, is ideally placed to witness the fall in China's birth-rate.

Five years ago, she recalled that there were about 40 children per class. Now, Wang said there are just 30 in the class for 5-year-olds and about 20 in the class for 4-year-olds. The figure is just 10 for the class of 3-year-olds.

This sort of anecdotal evidence is being backed up by hard statistics. By the end of last year, there were 225 million Chinese who were 14 years old or younger, which was 16.5 percent of the total population.