The number of childbirths in South Korea fell 10 months in a row in September amid a low birth rate and a late marriage trend, government data showed Thursday.

About 34,300 babies were born in September, down 5.8 percent or 2,100, from a year earlier, extending the streak to 10 months from December last year, according to the data compiled by Statistics Korea.

The number of marriages also fell 6.3 percent on-year to 17,800 in September, marking the lowest figure for the month of September since 2004 when it posted 16,571.

"Marriages are largely affected by the economic situation," said the statistics agency. "Rising youth unemployment rates and higher rent discouraged young couples from deciding to tie the knot."

Meanwhile, the September number of divorces and deaths gained 3.4 percent and 3.3 percent to 9,100 and 22,100 from a year earlier, respectively, the data showed.

Coupled with rapid aging, the low birth rate has been regarded as one of the biggest threats to the South Korean economy as it leads to a reduced workforce and increased welfare costs, undermining the growth potential of Asia's fourth-largest economy.

The latest census data showed that people aged over 65 years made up 13.2 percent of all 51 million citizens last year. Nations become an "aged society" when the demographic reaches 14 percent.

The country's fertility rate, or the average number of babies that a woman is projected to have during her lifetime, has hovered around 1.2 in recent years, despite the government's constant efforts to encourage people to have more children. (Yonhap)