The researchers said the study could not explain why sex education might have a stronger effect in delaying sex among teen boys and black girls, but Albert offered an explanation.
"It is the case that declines in sexual activity among teen boys, as opposed to girls, and African-American teen girls, as opposed to other racial/ethnic groups, have been much more dramatic over the past decade. This may, in part, explain why the effect of sex education seems stronger. It may also be that concern about HIV/AIDs may be particularly strong among these two groups," said Albert.
However, certain sub-populations of teens deserve further research, said Mueller. The data suggested that both rural, white teen girls and white or Hispanic teen girls who had dropped out of school might be more likely to have sex before age 15 if they had sex education, but Mueller said the number of people in those groups in the study was so small that the results could be a statistical fluke.
"They were kind of opposite findings," said Mueller, who acknowledged that "some subgroups may not benefit from sex ed the same way as the larger group of teens."
This research comes in the wake of data released Dec. 5 by the CDC showing that the annual rate of births to teens has increased for the first time in 14 years. Between 2005 and 2006, the birth rate for girls 15 to 19 rose 3 percent -- from 40.5 births per 1,000 in 2005 to 41.9 per 1,000 in 2006.
Considering both studies, Albert said, "The early wins may have been won. Future efforts may well have to be more intense, focused, and creative if the nation is to make continued progress in reducing teen pregnancy and childbearing. Put another way, yesterday's way of doing business will no longer suffice."
To find more data about teenagers and sexual decision-making, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Bill Albert, deputy director, The National Campaign to Prevent Teen and Unplanned Pregnancy, Washington, D.C.; Trisha Mueller, M.P.H., epidemiologist, division of public health, U.S. Centers for Disease Control and Prevention; January 2008, Journal of Adolescent Health