Friends explores issues among a group of 30-somethings

Researchers said watching or discussing a show with an adult reinforced or clarified the lessons carried by TV.

A Friends episode in which Rachel becomes pregnant after her former partner Ross's condom fails was watched by 1.6 million 12-to 17-year-olds.

Teenagers who watched or discussed it with an adult were about twice as likely to recall the issues involved.

Researchers interviewed about 500 teenagers shortly after the episode aired in October 2001.

Sexual attitudes

Viewers recalled the lessons six months later, according to the study in the November edition of the US journal Paediatrics.

The research was part of a study by California-based research group Rand into the role TV plays in teenagers' development of sexual attitudes and behaviour.

Rebecca Collins, author of the report, said: "We've always known that teenagers get useful information about sex from factual reporting and advice-oriented media, but now we know they can get this information from entertainment television programmes as well.

"When parents and kids watch television together, a programme may present an opportunity to discuss issues the children might not raise on their own."