Number of U.S. teens giving birth at a low

The number of American teens giving birth has dropped to an all-time low, federal health officials reported Tuesday.

"There has been a phenomenal drop [of 9 percent] in the last two years," said Brady Hamilton, a statistician at the Centers for Disease Control and Prevention.

Hamilton said the teen trend is a part of a larger one with the national birthrate. For all but older women, that has been dropping for some time, he said.

The rate stands at about 34 births per 1,000 of those ages 15 through 19. That's a 44 percent drop since 1991, according to the report. In 2010, teen birthrates by age and race and Hispanic origin were also lower than ever before, the CDC said.

Fewer babies were born to teens in 2010 than in any year since 1946. If the drop hadn't occurred, there would have been an estimated 3.4 million more births to teens from 1992 to 2010, the report said.

The U.S. teen birthrate is still among the highest for industrialized countries, however.

In looking to explain the dramatic drop, Hamilton said there's evidence that messages about sexual practices and the use of contraceptives have been successful.