Samantha, Miranda, Carrie and Charlotte: positive role models?
Influence
Sharon Hall, head of Personal Social and Health Education (PSHE) at Penwortham Girls' High School, says that one of the issues affecting adolescents' attitudes towards sex is the type of role model presented to young people by the media.
Ms Hall says: "There is a certain perception of some celebrities like Paris Hilton involved with drugs and alcohol. There are fewer role models who are academically successful.
"It's not just about sexual behaviour. Some celebrities dress more provocatively, even if they aren't acting in the same way.
"This causes some 12 or 13 year olds to aspire to that sort of look, without fully realising what that could lead to."
Tory MP Nadine Dorris said that a similar study in the UK would be interesting to see if a trend was revealed.
Different
Dr Helen Jones, a senior Film and Media lecturer at the University of Central Lancashire, agrees that the media influences young people's attitudes towards sex.
However, she says: "The provision of media as a public service in this country means that if this study were to be carried out in the UK, you would be comparing two completely different things."
The British media landscape is different from that of the US, where there are no national broadcast programming services. Public television plays a much smaller role, and television channels are commercial - broadcast solely for entertainment.
In the UK, corporations like the BBC are expected to provide a public service in exchange for a licence fee. Similarly, ITV and Channel 4 have a public remit.
Dr Jones says: "Over here, the main channels are designed to promote debate, social inclusion and education. They are aimed at different regions and age groups.
"The television in America is fundamentally commercial. There are fewer educational elements that could guide teenagers away from irresponsible sexual behaviour.
Export
"This fairly robust study suggests that we are exporting cultural values and behaviour from the US, as well as the media itself."
"You could argue that this is because the British media is becoming 'Americanised', with shows like Sex and the City and Friends now being exported as global products, and Sky and Freeview readily available in most UK homes.
The report comes as Britain's teenage pregnancy rates climb to the highest in Europe. Every year, almost 50,000 girls under 18 in the UK fall pregnant, The Daily Telegraph revealed in December 2007.
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Photographs courtesy of Flickr: Sex and the City and Friends (click on links to see original locations).