Annual live births fell to 49,796 last year from 79,790 in 1975, the Census & Statistics Department says. The ratio of annual births fell from 17.9 per 1,000 people to 7.2.

The department said most of the female baby-boomers born in the 1950s and 60s have reached the end of their childbearing age. This has led to the drop in the annual number of births, apart from the decline in the age-specific fertility rates.

Commissioner for Census & Statistics Frederick Ho said fertility statistics were previously compiled by counting all live births in Hong Kong in a year. The figure included births to Mainland women, regardless of whether their spouse was a Hong Kong resident. But births outside Hong Kong to Hong Kong residents were not included.

Under an enhanced approach, live births used in the calculation of fertility statistics include those born in Hong Kong to Hong Kong women, those born in Hong Kong to Mainland women with Hong Kong spouses, and those born outside Hong Kong to Hong Kong women.