Joan Smith: Oh, Melanie, put away your whip

It's the Daily Mail's dream story, an insultingly-named "baby factory" - actually a council house in Derby - where a single mother lives with three teenage daughters, all of whom have become mothers themselves. Confirming the paper's prejudices, the teenage mothers have named their infants T-Jay, Lita and Amani, which clearly demonstrates the ignorance of the working classes. With monikers like that, the poor kids have got absolutely no chance of marrying into the aristocracy nor even the rock branch of it, where Tara, Otis and Elton are de rigueur.

It's the Daily Mail's dream story, an insultingly-named "baby factory" - actually a council house in Derby - where a single mother lives with three teenage daughters, all of whom have become mothers themselves. Confirming the paper's prejudices, the teenage mothers have named their infants T-Jay, Lita and Amani, which clearly demonstrates the ignorance of the working classes. With monikers like that, the poor kids have got absolutely no chance of marrying into the aristocracy nor even the rock branch of it, where Tara, Otis and Elton are de rigueur.

For the Mail's moral guardian, Melanie Phillips - who should surely by now have amended her second name to Philippic - it was a heaven-sent opportunity to denounced the "moral degradation that is bringing increasing sections of our society to its knees". Phillips thundered about families in which "all standards of restraint and civilised behaviour have broken down". Actually, the young mothers seem to be quite fond of their offspring, which is not to say I am in favour of teenage pregnancy, but does suggest that members of the family have some sense of responsibility.

Struggling out of this thicket of moral condemnation, it seems to me that the problems with underage and teenage pregnancy are not so much moral as practical. As a general rule, children should not be brought up by children, while the young mothers themselves are unlikely to finish their own education, creating a cycle of low achievement. And while I understand the impulse to defend teenage mothers from the wrath of the Mail and The Sun, I'm not convinced either by Madeleine Bunting's argument in The Guardian on Friday that teenage pregnancy has been unfairly demonised. Bunting suggested that 17-year-old girls who get pregnant might be making a reasonable choice since they would not achieve much if they delayed having their first child, ignoring the fact that girls of that age rarely have the emotional maturity to cope with the demands of motherhood.

Younger girls are below the age of consent for good reasons, including the need to protect them from predatory men and the complexities of sexual relationships. Becoming pregnant may be a way of obtaining status and attention but it cannot compensate for losing part of their own childhood. At the same time, that short-term benefit has to be acknowledged if this country's alarming statistics on underage pregnancy are ever to be brought down to the levels of other European countries. The Mail's case against families like that of Mrs Atkins fails not just on that count but also in its language, which is little more than standard puritan invective. I can't listen to Phillips going on about the need for "absolutely rigid discipline" without picturing her in high heels, corset and a whip, although I'm sure none of these items has a place in her famously sensible wardrobe.

The puritan position on sex (so to speak) shares the same drawback as its approach to drugs, which is that it expects people to accept propositions they know to be untrue. There is no point in telling people who enjoy the occasional spliff that all drugs lead inevitably to crack addiction, just as it is nonsense to suggest that sex is always harmful unless it takes place in the marital bed and for the purpose of procreation. The message that needs to be got across to pubescent children is that sex in some circumstances - unprotected, at too young an age, with the wrong person - can be damaging, along with a cool exposition of the nature of that damage.

You won't find anything like that in the Mail, which ended the week with an exciting addition to its anti-sex agenda, this time a story suggesting that oral contraceptives can ruin a woman's sex drive. Before young girls start risking an unwanted pregnancy, I should say that the Pill never had that effect on me - you're quite safe, in my view, as long as you don't take it in conjunction with the Daily Mail.