Twelve-year-old girls will soon be arriving home from school with a leaflet about the human papilloma virus jag and a consent form for their parent to sign. If it were my daughter would I sign it? I'm not sure I would. I think my first reaction would be to sit my daughter down and have a long and measured chat about her options.

Twelve-year-old girls will soon be arriving home from school with a leaflet about the human papilloma virus jag and a consent form for their parent to sign. If it were my daughter would I sign it? I'm not sure I would. I think my first reaction would be to sit my daughter down and have a long and measured chat about her options.

I think I'd weigh up the odds.

HPV is a sexually transmitted virus. The proposed vaccination offers protection against the two most dangerous strains, which cause cervical cancer. The scheme is deliberately targeting children because the vaccinations are most effective before girls embark on a sex life.

It will anger some parents that such young girls are being confronted with issues such as sexually transmitted diseases (STDs), but however tempted they are to protect their child's "innocence", they have no choice but to confront this reality. The jag is featured in a TV advertising campaign pitched directly at the girls, not at their parents. It is bound to be talked about in school so the child will be informed, or misinformed, by friends if this is not discussed at home. Besides, there is a decision to make.

Also, even at the age of 12, each girl has the legal right to opt for the injection even if her parents refuse it - and to refuse it even if they accept. The law recognises that it's her body that is about to be invaded or protected - according to your viewpoint. The decision is hers. It follows that she should be fully informed on the matter.

Once she is, she may not feel the need for the jag - at least not yet.

What the injection offers is protection against cervical cancer. It's a killer that claims around 100 lives a year in Scotland - and girls who are sexually active before their bodies are fully mature are thought by some doctors to have a heightened risk of developing it. For many girls and their parents that will be argument enough. They will opt for the injection and be grateful for the protection. But it isn't as simple a decision as the television advertisement suggests.

Statistics show that only 6% of adult women say they indulged in sexual intercourse before they were 16 years old. Even allowing for the figures to have increased, that is a small percentage. What the parent needs to assess are the chances that their daughter will be one of the minority. If it were my child, I would pause to make that calculation as dispassionately as I could.

I wouldn't rush at the jag because it seems to me that today's girls have a high enough chemical intake. They have the usual measles, mumps, polio, tetanus and rubella inoculations. Now they will also have three anti-HPV injections. Thereafter, (and hopefully not until their late teens or twenties) a high percentage will start taking the contraceptive pill. Some will also resort to the morning-after pill from time to time. When they grow older still they will swop their contraceptive pill for HRT. Thus, from pre-pubescence to their pension they will have been absorbing chemicals by needle or mouth. Is that a good thing, bearing in mind that they are born with the eggs that will become the next generation?

It is, of course, a matter of balance. I am pleased to have had a life thus far free from all the ills these pills prevent and I want to see girls protected from disease. But isn't it time that men carried some of the cost and responsibility of this shared business of sex and reproduction and its untoward side effects? It is only women's bodies that are doctored. Why?

Since it is men who spread the HPV virus, why aren't boys in the UK required to be immunised? (The vaccine is licensed for boys in Australia.) The literature says boys respond less well to the vaccine. But the mere fact of making this a shared inoculation would flag up their role in the dissemination of the virus. It would send out the message that boys, too, have responsibilities. They should be made ultra aware before they start a relationship of the need to protect their partner and themselves by using condoms.

But back to the risk/benefit analysis for girls. Parents are asked to remember that three jags will protect their daughter from cervical cancer. A browse of the frequently asked questions on the government's website reveals that the protection lasts for six years. (It might last longer but there is no certainty.) That means girls will have protection until they are 18. In other words, it might run out just when many of them are most likely to become sexually active.

I know the government wants to vaccinate young to protect the greatest number. But if it were my child I would be advocating that she delay sexual involvement until she is mature enough to cope with it - and that she delay the jag until she is contemplating a sexual relationship.

Research shows that the more information a young person has, the greater is the likelihood that they will delay their first sexual encounter and the greater the likelihood that they will use contraception.

It makes sense. The ignorant young romantic is much more likely to be rash and impulsive than a girl who understands that a brief sexual encounter can bring in its wake genital warts, chlamydia, syphilis and gonorrhoea - not to mention an untimely pregnancy.

Exchanging the birds and the bees for the warts and the STDs is more likely to disillusion than to inflame. Girls start asking (like Scarlett O'Hara did) "What's in it for me?"

I'm not suggesting that any teenager will come to their father or mother and announce their intention to sleep with their boyfriend. The point is they can get the jag without telling their parents. That is the middle way I would aim for.

Through its advertising campaign, the government has put control and decision-making into the hands of these children. But it is also doing a disservice, for it presents the issue as if the girls have only one option. The intention is to have them fall into an orderly line to receive the injections en masse.

But it is entirely legitimate for the girls to look to what is in their own best interest. After all, why should those who have every intention of waiting until they are adult before starting an adult life be injected now? By that stage they might choose to insist on a condom, and/ or ask their prospective partner to be tested for the two lethal strains of the virus before sleeping with them. They might also have regular cervical smears to detect early changes that could indicate a treatable pre-cancerous condition.

The government has flagged up one option for the girls. It has failed to tell them there are others. That is the parents' job. When they have done it, it will be up to the girls to choose.