The number of babies born in South Korea dropped for the first time in four years in 2013, a report showed Thursday, deepening worries for a country whose already low birthrate undermines its growth potential.

According to the report by Statistics Korea, 436,600 babies were born last year, down 48,000 or 9.9 percent from a year earlier.

The number marked the lowest since 2005 when 435,031 babies were born. It also represented the first time that childbirths have declined on a year-on-year basis since 2009.

The report said that the total fertility rate, or the average number of babies that a woman is projected to have during her lifetime, dropped to 1.19 last year from the previous year's 1.3.

The crude birthrate -- the number of babies born per 1,000 people -- also fell to 8.6, the lowest level since related record-keeping began in 1970, the report showed.

Concerns persist that the chronically low birthrate will result in a smaller working population going forward, eventually hurting the country's economic growth and undermining its longer-term growth potential.

The report underlined a growing trend among South Koreans to delay having babies.

The average age for women having their first baby stood at 30.73, up 0.23 from a year earlier. This is the highest since 1993 when the statistics agency started to compile related data. The average age for a woman to have her first child at the time was 26.23.

The ratio of "older women" giving birth also continued to rise, with those aged 35 and older accounting for 20.2 percent of all women who had babies last year. It was higher than the previous year's 18.7 percent, the report showed.

In a separate report on population mobility, the statistics agency said that the number of people changing their official residence in January dropped 4.7 percent on-year to about 580,000. The decline is due in part to the protracted property market slump, experts said. (Yonhap)