NEW YORK • The birth rate among teenagers in the United States has fallen to a historic low, with births by black and Hispanic teens down by nearly half over the past decade, the Centres for Disease Control and Prevention (CDC) said.

Birth rates for all American teenagers are down 40 per cent since 2006, thanks in part to prevention programmes that address socio-economic conditions such as unemployment and lower education levels, a CDC report said on Thursday.

But officials said the birth rate was still too high, especially for minorities, and more work was needed.

The annual survey shows the continuation of a downward trend that began in 2006 and continued through 2014, the latest year of complete data, when nearly 250,000 babies were born to girls aged 15 to 19.

The birth rate of 24.2 per 1,000 women in this age group is down 9 per cent from 2013 and the lowest among 15-year-olds to 19-year-olds since 1940, the CDC said.

For black teens, the 2014 rate was 34.9 per 1,000, and for Hispanics it was 38.0.

"While reasons for the declines are not clear, teens seem to be less sexually active, and more of those who are sexually active seem to be using birth control than in previous years," the CDC said.

But officials said the rates were too high.

According to a report published last year by the Journal of Adolescent Health, the US had the highest teen pregnancy rate among 21 counties with complete statistics, with 57 pregnancies per 1,000 females from 2008 to 2011. Switzerland had the lowest at eight per 1,000.

In some American states, birth rates for black and Hispanic teens were more than three times higher than the rate for whites, the CDC said.

REUTERS