The US teen birth rate compares to that of the United Kingdom, with 24 births per 1,000 girls. Italy and Japan have only 5 per 1,000, Jacobsen said.

The US rate dropped by one-third to 40.5 from 1991 to 2005, but data from 2007 suggested a reversal of this trend, the report said.

US government data from 2007 showed the birth rate among Hispanic teens in the US to be 81.7 per 1,000 girls. The rate for African-American teens was 64.3 and the rate for non-Hispanic whites was 27.2, according to the Center for Disease Control and

Prevention.

Teen pregnancy in the US often leads to high-risk pregnancy, lower educational achievement, unemployment and poverty. These risks are amplified by the aging US population and the changing demographic.