With the exception, perhaps, of rampant exhibitionists, doggers and members of the mile-high club, everyone wants details of their sex life kept private. And though it may be difficult to accept, that goes for most underage young people too. When a sexually active 13-year-old goes to see her doctor with suspected chlamydia or a contraceptive request, she expects that the information she shares will remain confidential.

And up until now, it will. Unless the doctor has reason to suspect the teenager is being sexually abused, he or she is under no obligation to pass on the girl's name to social services or her parents.

But not for much longer. The government is currently consulting on a new version of its guidance on child protection, a document entitled Working Together to Safeguard Children. If this revision is passed as expected, it will include protocols that require health professionals to report any sexually active children aged 13 or under, however consensual the sex, to the police and social workers.

It's a huge deal. Confidentiality is one of the cornerstones of medical practice. It's the glue that holds the doctor-patient relationship together and is enshrined in the Hippocratic Oath and enforced by the General Medical Council. Doing away with it is like removing the fifth amendment from the American constitution.

Of course, the revision is being made in good faith, triggered by the Bichard inquiry into the circumstances surrounding the deaths of Holly Wells and Jessica Chapman in Soham. But it has been ill-thought through.

The aim is to protect vulnerable teenagers from sexual abuse. But there's real concern among doctors groups and sexual-health charities that it will instead cause this vulnerable group to completely shun all the help on offer.

The Brook advisory service recently carried out a survey among teenagers, which showed overwhelmingly that this group values confidentiality above all else when it comes to sex. Two-thirds of respondents - and a massive 91% of under 16s - said they would be less likely to seek advice on issues such as contraception, pregnancy and sexually transmitted infections (STIs) if they knew that health workers were going to turn them in to the authorities.

According to an editorial in this week's British Medical Journal, more than a quarter of under-16s are now sexually active. And Britain currently holds the European record for teenage pregnancies. We know that those who start having sex under the age of 13 are nine times more likely to have multiple sexual partners than those who wait until the ripe old age of 15. They are therefore at greatest risk of picking up STIs such as chlamydia and the human papilloma virus, which has been implicated as a trigger for cervical cancer. It's also known that they are more likely to develop psychological problems than other teenagers .

Frighten this group off and we will miss any opportunity to encourage safe sex, discuss contraceptive methods and have any influence over the way in which they conduct relationships.

Of course, some of these children are at risk of abuse and we obviously have a duty to protect them and pass on our concerns to child protection agencies. But a blanket instruction to do so in all cases could actually put some teenagers at greater risk by keeping them away.