Lauren Booth, sister of Cherie Blair and contestant on last year’s I’m a Celebrity . . . Get Me Out of Here! started a debate last week when she wrote that middle-aged women should glory in “letting themselves go”.

“Why can’t women slide comfortably into middle age?” she asked. “Why is there such wretched pressure on us to look good all the time? . . . Why does there have to be such a terror of becoming a little dowdy?”

Booth is 39 and a mother of two. Her protestations resulted in another journalist, Helena Frith Powell, opining that “your late thirties and early forties are not the time to take your eye off your waistline or your wrinkles — if you do that, you’re doomed. It is time to take them on head first and make damn sure you win”.

This is all to do with having children: children are what cause you to pull on the jogging bottoms, banish the heels and devote less attention than you might to the question of regular blow-dries. It is also, more specifically, to do with the self-esteem-sapping myth of the yummy mummy, which seems in danger of taking over the world.

This is mad, because yummy mummies don’t exist, or rather they exist in such a rarefied sphere that most people will never encounter one. You are a yummy mummy if you are a) Kate Moss or b) a trophy wife married to a banker whose annual bonus exceeds £2m. And, er, that’s it.

Everything else is aspiration, self-delusion and pretence — the stuff women use to make themselves feel better, not realising that it’s making them feel worse because it adds another strand of unnecessary competitiveness to the boringly complicated business of being female.

Yummy mummies didn’t exist when I had my first child 14 years ago. Some mummies were slightly less knackered-looking than others, but that was about it. Some mummies — one or two — had maternity nurses, nannies and armies of staff and looked well rested, but they didn’t count since they didn’t, as far as anyone could work out, do any mummying. And yet it is this last category — unimpressive on the parenting front, if financially fortunate — that we are all now supposed to want to emulate.

I have some difficulty understanding this, because to me the advantages of being a parent are not visual: you don’t become one because it’s going to make you look hot. Besides, you can be as hot as you want but that isn’t by a long stretch what parenting is about, at any level. So you just end up looking weirdly vain, pushing your Bugaboo pram and flicking your highlights like you’re Gwen Stefani, inviting people to admire your utterly immobile Botoxed yumminess.

Is this not a little needy? A tiny bit desperate, given that you could be lying in bed with your baby, bouncing or reading, or you could be at the park in all your unbrushed, ungroomed glory with the other knackered-looking mums, having a nice chat and feeling part of something friendly and warm. I’m sure the point of aspirant yummy mummyhood isn’t to parade your insecurities in public, but I’m afraid that’s more often than not what it looks like.

It’s no coincidence that the rise of the yummy mummy, so-called, should have dovetailed with a rise in women having their first child when they are no longer in the first flush of youth. That’s what this self-sabotaging silliness is really about: clinging on to youth, to beauty, to feeling sexually desirable when you’re no spring chicken and when you’re knackered from looking after your squalling infant.

Have a first child at 25 and you don’t care what you look like: your whole world becomes about your lovely baby. Have a first child at 40 and a degree of panic sets in. You must look youthful! You musn’t look like you managed to bang one out before you were pensionable! You must look fertile, radiant, primped and groomed — not like (horror) the oldest mother at the school fete.

So you dye, you pluck, you diet, you wear cashmere sweaters that get covered in sick three times a day (and that you handwash, as if life wasn’t short enough already). You totter about at parties in heels and a foxy little dress and you die of pleasure if anyone says that you look amazing and not at all like you’ve just had a baby.

It seems a shame to refuse to embrace the thing you so craved and to go out of your way to pretend it hasn’t happened — toned stomach, birdlike appetite, obsessive yoga: in a new mother none of these things scream chilled-out contentment.

As for letting yourself go: I wish women realised that, where other women are concerned, some (unglamorous) things are badges of honour. They include exhaustion, stress, anxiety, looking weird on your first day back in the office because you’ve forgotten how to dress for work, crying feebly at anything remotely sentimental even though you’re technically a hardened cynic, and so on. These are the things that bind us to other women — a shared experience of having gone through something seismic and life-changing. These are the things women respond to.

It is often said that women are each other’s worst enemies and the debate about “letting yourself go” shows how true (alas) the maxim is. I believe in vanity; I don’t think letting yourself go is a self-loving thing to do — it’s saying, “Being considered attractive is no longer of any interest to me”, which is sad when you’re not yet 40.

Besides, I don’t quite buy it because it’s also saying, rather passive-aggressively, “my domestic contentment is far greater than yours so I don’t need lipstick”. I understand why new mothers let themselves go — it’s hard to care about this season’s hemlines when you’re in love with your baby and dizzy with tiredness — and I think it is absolutely right that they should. And I think it’s also absolutely right that they should at some point get back in shape — when they’re good and ready. There’s nothing life affirming about being three stone overweight and wearing tents.

As for “sliding comfortably into middle age”: why should this involve abandoning anything? The very idea suggests a kind of gradual petering out, as does the accompanying unspoken notion that women somehow welcome the kind of invisibility that comes hand in hand with wearing sacks and not doing your hair.

I can see why some women go so far the other way and make outlandish attempts at remaining visible. But I wish everyone would relax a bit. It’s not a competition. And you can love your children while still loving yourself.

India Knight has a blog: Isn't She Talking Yet? for parents of children with special needs

Many Times and Sunday Times writers contribute to our blog for working mothers: Alpha Mummy

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