from www.dailymaIL.CO.UK – Girls as young as 15 are taking part in group sex, with more than half being coerced into doing it, a study has revealed.

Researchers at Boston University’s School of Public Health found one in 13 teenage girls reported having a ‘multi-person sex’ (MPS) experience – often initiated by boyfriends who had been watching pornography.

The average age of the girls who had experienced MPS was just 15.6 years old – under the legal age of consent in Massachusetts, which is 16.

And nearly half of those said their sexual partners did not use condoms, raising concerns over the spread of sexually transmitted diseases.

The study, of 328 girls from deprived areas in Boston who had gone to sexual health clinics, raises concerns about the influence of pornography on teenagers.

Emily Rothman, associate professor of community health sciences at the school, told philadelphiaweekly.com: ‘Girls were five times more likely to engage in MPS if they or their boyfriends had watched porn.

‘Out of those who engaged in MPS, 50 per cent did things their partners saw in porn first. Porn may be influencing the sexual behaviour of these teens.’

She added that more than half of girls who engaged in some form of group sex ‘were pressured or coerced into a gang rape – or a boyfriend would ask them to do a three-way’.

A third of those who had experienced MPS had also used alcohol or drugs before.

The study, published in the Journal of Urban Health, reveals more research is needed in the link between highly sexualised images and decision-making in terms of sex and relationships among teenagers.

It cited another study of high-school girls in the U.S. north east that found ‘sex parties’ had become an ‘accepted activity’ among some teenagers.

Ms Rothman is applying for grant funding to research the link between dating violence and pornography.

Pornography is increasingly available to teenagers through the internet and many are exposed to sexualised images through music stars and fashion models.

‘We need to know more about how adolescents’ and children’s experiences are shaped by hyper-sexualised images they see on regular TV and ads. It’s a worthwhile question.

‘Group sex among youth is an important public health topic that has received very little attention to date.

‘It’s time for parents, pediatricians, federal agencies and community-based organisations to sit up, pay attention and take notice: group sex is happening, and we need to be prepared to address it.’