Frightened by the high costs of child care, many young people in Hong Kong choose to raise cats and dogs instead. The city's fertility rate has fallen from 2.0 children per woman in 1980 to 1.3 in 2012, according to World Bank data, lower even than that of the mainland, which has in place the one-child policy and has a birth rate of 1.7 per woman.

A new calculation is putting a price tag on that cost.

According to calculations by nonprofit Hong Kong Bauhinia Foundation Research Centre, the cost of raising a child from birth to college graduation in Hong Kong averages about 5.5 million Hong Kong dollars (US$710,000) for a middle-class family.

(A recent calculation by the U.S. Department of Agriculture showed that the average cost for a middle-class family to raise a child to the age of 18 was $245,340—excluding college tuition.)

Data the foundation collected showed that many children of middle-class families in Hong Kong usually start attending playgroups and pre-school preparatory classes when they are just a year old.