In yet another attempt to curb Britain's alarming rate of young teenage pregnancy, a group of schools in Southampton is now providing 13-year-old girls with "secret" contraceptive implants.

That is to say, the implants - which give contraceptive protection for three years - are offered to pupils without parents' consent, although the schoolgirls may choose to inform their parents.

The practice may be more widespread throughout England and Wales than is as yet acknowledged; but the Southampton schools were among the first to offer sexual advice clinics for young teenage girls.

One 13-year-old schoolgirl who has spoken about the procedure says she is very pleased she made the decision. She said she "wanted to have sex and the implant works well". She adds"I think it has really helped me because if I am with my boyfriend and we feel like having sex, I have the peace of mind of knowing I am okay." She has since told her mother, who praised her daughter for her "adult" decision.

Still, not all parents are happy about this trend, which is likely to spread to more schools in the UK. It makes a mockery of the idea of the legal age of consent, which is supposed to be 16. If a girl of 13 has been fitted with a contraceptive implant, surely this is the equivalent of giving the green light to sexual activity at 13?

And isn't there a double standard, then, in talking about "child abuse" of victims of 13 and 14, if such young people have actually been given the wherewithal to have sex by the authorities? It blurs barriers between "child abuse" and "teenage consent".

Parents also worry it is yet another area where the state is invading the rights of the family and the home. An underage youngster is not supposed to have any kind of an operation or medical intervention without parental consent; but this obviously breaches the protocol.

And even if a young girl is protected from pregnancy - the Hampshire Health Service Trust has said they are confident that there is already a reduction in young teenage pregnancies - it still leaves her vulnerable to sexually transmitted disease, and the emotional upsets of "too much, too young". Studies have shown that many young women regret embarking on a full sexual relationship too early.

And yet, for the advocates of sexual health clinics in schools, the contraceptive implant represents the "lesser evil" of a pregnancy at 13 or 14, followed by either an abortion or a baby, both of which are more distressing for a young girl than a mere hormonal implant.

The problem of sexually active young girls is not new, although some of the circumstances today are different and some of the pressures greater. Societies have always tried to protect young girls from early sexual experience, either by law, custom, taboo or stigma. A hundred years ago, girls having early sexual experience were called "moral imbeciles" and sometimes consigned to a mental asylum. Others drifted, sooner or later, into prostitution, because they were "damaged goods" in respectable society. Males were seldom subject to the same restraints for the simple biological reason that males did not become pregnant, and thus there was no evidence of sexual activity.

In our age of equality, girls and boys are supposed to be subject to the same laws and the same treatment, but the biological fact still remains intractable: it is the 13-year-old girl who will get pregnant if she has unprotected sex. Thus the implant idea.

And there are enormous pressures on young girls today. The internet is awash with sexualisation and with pornography. Social networks increase pressure on youngsters to be sexually active, and young girls are frequently bullied, and called "frigid" and "lezzies" if they remain virgins once into their teens.

Yet they can also be bullied and disparaged if they are perceived as promiscuous, and taunted as "slags" and "tarts". Self-harming, eating disorders and even suicide among young girls have been linked to these social pressures.

Today, there are cultural (and maybe also commercial) influences against any suggestions that very young teenagers should, perhaps, wait until they are older until they embark on full sexual relationships. Deferred gratification is an archaic notion where "must have" and "I want it now" have been the accepted norm.

A Catholic member of parliament for Liverpool, Nadine Dorries, was howled down as a "repressive" reactionary when she suggested it mightn't be a bad idea to teach abstinence to 13-to-16-year-olds, along with sensible sex and health education. She was accused of returning to the days of "lock up your daughters", when chaperones kept a beady protective eye on the nubile female.

Only long-term studies will show whether the contraceptive implant does reduce the statistics on teenage pregnancy: and whether, too, it erodes the age of consent, and rights of parents.

But I imagine that most mothers - and fathers - of young teenage girls will still hope that their daughters can defer becoming sexually involved at such a very young age. It is surely better for their own self-worth and development if they can wait until adulthood. The story of Romeo and Juliet is not just about star-crossed teenage love; it is also about the hotheadedness of youth ending with inevitable tragedy.