Less Smoking, Sex Among U.S. High School Kids: CDC
But rates for other unhealthy behaviors, such as texting while driving, are up, agency says
"Although this report doesn't have data on e-cigarette use among high school students, we know that e-cigarette use is skyrocketing, and we are concerned about that," Frieden said. "We are particularly concerned with e-cigarettes 're-glamorizing' smoking traditional cigarettes."
And when it comes to sexual activity, the survey found that the rate of unprotected, condom-free sex has actually risen over time. In 2003, 63 percent of sexually active teens said they used condoms, compared to 59 percent in 2013.
The rise of computer and wireless technologies may also be taking a toll on the health and safety of young people. The CDC survey found a dramatic rise in the number of teen drivers who text or email while on the road: In 2013, 41 percent of teen drivers said they had done so at least once over the past month.
"Texting while driving continues to be a concern," Dr. Stephanie Zaza, director of CDC's division of adolescent and school health, said during the news conference. "Teen drivers have the highest proportion of distraction-related fatal crashes," she noted.
"Parents can play an active role in keeping their teen drivers safe by close monitoring, frequent discussion, parent-teen driving agreements and acting as a role model of good driving habits," Zaza said.
And while fewer kids are now watching three or more hours of TV per day than in the past, computer time may have taken its place. According to the CDC survey, the percentage of teens who say they spend three or more hours each day on their computers (for non-schoolwork-related purposes) jumped from 22 percent in 2003 to 41 percent 10 years later.
"We know that excessive screen time -- such as TV, computer or video game use -- is associated with chronic diseases and factors such as obesity," Zaza noted.
The exact reasons for the trends noted in the new report aren't clear, she added. The survey "tells us what kids do, but not why," Zaza said.
Frieden said more must be done to make sure the nation's children grow up healthy.
"It's not too much to ask that every kid born in this country reaches adulthood without an infection that they will have to deal with for the rest of their life, without nicotine addiction and at a healthy weight," he said.