Researchers interviewed 2,000 adolescents aged 12 to 17 three times between 2001 and 2004 and found that those with the highest exposure to sex on television were twice as likely to be involved in a pregnancy than those with the least exposure.
"Adolescents receive a considerable amount of information about sex through television and that programming typically does not highlight the risks and responsibilities of sex," said Anita Chandra, the lead author and a behavioral scientist at RAND, the nonprofit research organization that funded the study.
"Our findings suggest that television may play a significant role in the high rates of teenage pregnancy in the United States," she said.
Researchers said the study demonstrated that programs with sexual content create the perception there is little risk of sex without contraception.
By the third interview, 744 of the 2,000 teenagers in the survey said they had engaged in sexual intercourse and 718 of the youths shared with RAND information about their pregnancy histories.
Of that group, 91 teens, 58 girls and 33 boys, were involved in a pregnancy.
The rate of teenage pregnancies has increased for the first time in 15 years, measuring 41.9 births per 1,000 Americans aged 15 to 19 years in 2006, according to the Center for Prevention and Disease Control (CDC).
"The amount of sexual content on television has doubled in recent years, and there is little representation of safer sex practices in those portrayals," said Chandra.
The findings have implications for broadcasters, parents and health care providers, she added.
The US has one of the highest teen pregnancy rates among industrialized nations, with nearly one million adolescent females becoming pregnant each year, with the majority of these pregnancies unplanned, according to RAND.