Rebecca Collins, PhD, of RAND Corporation, and colleagues did phone interviews with nearly 1,800 young people aged 12 to 17 about their sexual activity and TV viewing habits. They responded to measures of more than a dozen factors known to be associated with teen sexual initiation.
One year later, they called participants again to note what shows they watched and new sexual experiences the teens had experienced since the first survey.
The researchers, who conducted the interviews in 2001 and 2002, saw "substantial associations" between the amount of sexual content viewed by the teens and advances in sexual behavior.
In the year between the surveys, the teens with the most TV sex viewing were nearly twice as likely to have started having sexual intercourse as those who watched the least sexually charged shows.
All that racy content made kids grow up faster.
Twelve-year-olds who watched the most TV sex in their age group were similar to youths two to three years older who watched the least sex on TV of their peers.
It's hard to avoid sexual content on TV, which is part of nearly two-thirds of all TV programs.
The issue isn't just about scenes with sexually explicit content. Dialogue about sex can be just as influential.
"It apparently makes little difference whether a TV show presents people talking about whether they have sex or shows them actually having sex," write the researchers.
"Only about one of every seven TV shows that include sexual content includes any safe-sex messages, and nearly two-thirds of these instances (63%) are minor or inconsequential in their degree of emphasis in the scene," write the researchers.
That makes it tough to figure out whether safe-sex messages in TV shows can slow down teen sexual activity. The researchers saw some impact among black participants, but there wasn't enough material to draw more conclusions. They say that their study showed that black youths who watched more depictions of sexual risks or safety were less likely to initiate intercourse in the follow-up year.
An estimated 46% of U.S. high school students have had sexual intercourse. The U.S. teen pregnancy rate is among the highest of all industrialized countries, and for every four sexually active American teens, one case of sexually transmitted disease is diagnosed annually, according to the study.
Short of turning off the TV or radically changing programming, the issue isn't likely to go away.
Instead, parents may want to watch TV with their children and discuss risks and decisions related to the shows' sexual content, suggest the researchers.
That kind of perspective isn't likely to be found with a remote control.