China’s population growth has been slowing for decades as a combination of rising incomes and a restrictive one-child policy reduced births in the world’s most populous nation. The possibility of a declining population in coming years — the first time since the early 1960s — would mark a key milestone for the country and have broad implications for economic growth prospects and government finances.

Many major economies saw births slump last year during the pandemic as economic and socialdislocation undercut people’s desire to have children, and even China’s success in containing Covid-19 relatively quickly didn’t help the country arrest the decline.

The government didn’t disclose birth figures in the census.

According to separate data in February, the number of registered births declined by almost 15% in 2020 from the previous year.

The share of the working-age population — those between ages of 15 and 59 — slumped to 63.4% in 2020 from more than 70% a decade ago, according to the census. Residents aged 60 and above accounted for 18.7% of the population in 2020, up from 13.3% in 2010.

The urbanization momentum continued, with 63.9% of China’s population living in cities last year, up from 49.7% in 2010. That puts the country on track to meet the target of making 65% of the population urban residents by 2025.