Spare a thought for today's model mother: she's no sooner out of labour than she's back on the catwalk or the cover. But where are the stretch marks? By Ruth Picardie
Child as fashion accessory we've seen before: American supermodelette Niki Taylor plus one-year-old twins on the cover of Harper's Bazaar; little Le Bon-ettes toddling along the catwalk. But something new is happening to babes and their babes.

In the latest OK! Weekly, Pamela Anderson welcomes readers into the beautiful Californian mountain-top home she shares with Motley Crue drummer Tommy Lee and their nine-day-old baby, Brandon. "Making love when Pamela was very pregnant was just unbelievable," says Tommy, gently. "Before you ask," adds Pammy, smiling, "I'm feeding him myself. Yes, they work!" Here they are snapped sharing this beautiful time together, proud dad Tommy in leathers, pierced nipples and "Mayhem" tattoo, little Brandon clamped to a mogul-size cigar. Pammy's the one in crop top, PVC trousers and six- inch heels.

In the latest issue of Vogue, meanwhile, "model mothers" (pun intended) Debbie Dietering and Meghan Douglas frolic thinly on the beach in red mules (pounds 100) and body-skimming jersey (pounds 390) to "show how effortless holiday dressing can be", while babies Orion and Kelly are - yes, I'm afraid so - fat, not crying and totally unsmeared with baked beans.

Now we all know celebrities aren't like the rest of us, but this is ridiculous. While the American baby bible What To Expect The First Year warns post- partum mothers to expect fatigue, sometimes bordering on exhaustion; pain, discomfort and numbness in the perineum; continuing bouts of constipation; breast discomfort and nipple soreness; achiness in arms and neck; backache; and noticeable hair loss, Pammy - all shiny hair and glossy lips - looks like she's about to have sex. "As it happens," she explains, "I've already lost all the extra weight except for 5lb." Six months into motherhood, meanwhile, when most of us are learning to live with our stretch marks and sagging stomachs, Debbie and Meghan look as if they have never given birth.

Clearly no one expects the modern mother to make her first public appearance propped up in bed in a pink flannelette nightie and thereafter appear in M&S floral separates. Nevertheless, something very odd - even by Californian standards - is going on. Demi Moore posed in body paint for Vanity Fair seven months after giving birth to her second child. Rachel Hunter modelled a swimwear calendar just 12 weeks after her first child was born. Yasmin Le Bon was back on the catwalk 20 days after Saffron came along. And now Pammy puts on her PVC trousers after nine days.

All mothers suffer from the cult of perfection that surrounds pregnancy and birth. We are supposed to bloom for nine months; experience existential bliss during the primal joy of drug-free labour; bond instantly with the blob we have just produced; fancy our husband the next day; and be back to a size 10 by the six-week check.

Have just a little sympathy, therefore, for the A-grade celebrity, who has to be even better at motherhood than anyone else. Pammy loved being pregnant ("It made me feel more sexy, more womanly, more feminine. Carrying a baby made me feel like a real woman. I wasn't a little girl any more."); her labour involved "no gas, no air, no epidural; breastfeeding has been "no problem at all". Now, says Pammy, "the only time we fight is over who's going to change the baby, because we both want to". And, naturally, the blubber has simply melted away.

Even C-list Hello! fodder like Jane Seymour feel the pressure to perform post-natally: at 44, after her third pregnancy, having just produced twins, she told the magazine: "Ten days after the Caesarean I weighed two pounds lighter [sic] than when I started - which is unbelievable. I lost weight. And I didn't lose my stomach muscles, which is amazing, because first of all when you have a twin pregnancy, normally the muscles split. Somehow or other, I guess from all those years of ballet, it hung in there. I don't know where the skin went. I was huge. I was 1541b and I'm 1161b now. So almost 401b disappeared."

Of course, money makes it easier to be a perfect mother. Pammy Anderson looks bouncy not because of all the silicone she is carrying but, presumably, because she has a housekeeper to sterilise the dummies, a driver to pick up fresh supplies of Pampers, a maternity nurse to get up in the night - and, of course, a personal trainer to help with those pelvic tilts. Even Jane Seymour has her own gym.

But the mystery of the post-natal superbabe is more than projecting perfection, for the celebrity mother is compulsive in returning to her pre-pregnant shape. Rejecting a body double, Demi Moore postponed filming of her forthcoming schlocker, Striptease, to allow her time to get in shape after the birth of her third child. Six days a week, personal trainer by her side, she rose at 4am and spent two hours in her gym, before slipping into quality mom mode. Then it was back to sit-ups (2,500 a week), cycling, running, swimming, aerobics ... a titanic struggle against nature, or what's left of it, since Moore has reportedly had breast implants; liposuction on her thighs, stomach and bottom; and pockets of fat removed from behind her knees.

With Yasmin Le Bon and Rachel Hunter, the effort is understandable: a model is, after all, just a body. Presumably, Hunter's swimwear catalogue helped to pay the nanny - or maybe that was the fee as presenter for the US high-achiever's TV series How To Make It The Best Nine Months Of Your Life. Whatever, Debbie and Meghan are simply signalling to advertisers that they are ready to work again. Similarly, swimming champion Sharron Davies resumed training a few days after giving birth so that she could compete in the 1994 Commonwealth Games.

But Pammy Anderson is not just a model. She has put the Playboy centrefolds behind her to become the biggest television star in the world. Demi Moore, meanwhile, has shut the door on her trailerpark childhood to become the highest-paid actress in Hollywood.

Strangely, Moore's co-stars - Robert Redford in Indecent Proposal, Michael Douglas in Disclosure - have never appeared nude on the cover of Vanity Fair. Strangely, her co-stars have never had to get up at 4am to work their buns. Strangely, David Hasselhof is the boy hero of Baywatch despite the fact that he's obviously in his forties.

For in the looking-glass world of female stardom, women have to be babes, however powerful they are, however well-paid and however young their babes. No doubt Madonna - pregnant but ever-watchful of her fading stardom - will be working out during the delivery itself, before welcoming OK! into her lovely private hospital.

John Walsh's column is on page 21 of Section 1.