BEIJING — The number of babies born in China last year fell to a nearly six-decade low, exacerbating a looming demographic crisis that is set to reshape the world’s most populous nation and threaten its economic vitality.

About 14.6 million babies were born in China in 2019, according to the National Bureau of Statistics. That was a nearly 4 percent fall from the previous year, and the lowest official number of births in China since 1961, the last year of a widespread famine in which millions of people starved to death. That year, only 11.8 million babies were born.

Births in China have now fallen for three years in a row. They had risen slightly in 2016, a year after the government ended its one-child policy and allowed couples to have two children, a shift that officials hoped would drive a sustained increase in the number of newborns. But that has not materialized.

Experts say the slowdown is rooted in several trends, including the rise of women in the work force who are educated and don’t see marriage as necessary to achieving financial security, at least for themselves. For Chinese couples, many cannot afford to have children as living costs increase and their jobs demand more time and energy. And attitudes have shifted.