Six months after giving birth to her daughter Eva, Orlaith McAllister had her breasts done, going from a C-cup to a D-cup. "I breastfed for five weeks and I noticed that my breasts had got smaller, especially on one side," she says. "When Eva was born, she latched on to the left breast immediately and got to like that one, so it was noticeably smaller." She didn't feel that she had to have surgery, she says, just that she wanted it. "I'd been through all that pain and I just wanted to enjoy my body again."

McAllister, 28, lives between London and Belfast. Eva is now 10 months old. "Some women let themselves go," she says. "If they're comfortable with that, that's fine. But I believe that's how you get into a state of depression after you have a baby, because you don't like yourself any more. In my pregnancy I did everything to still be me: I ate healthily and exercised - I only put on a stone." She intends to have more children: "I want to have four more babies. I don't want a breast operation after every one. But for now I am just looking after myself: this is my life and I'm not hurting anybody else by doing it."

Perhaps this kind of surgery is not entirely surprising. McAllister is a model (she appeared on Big Brother series six) and already had experience of surgery - she had had breast implants before having children. But she is part of a growing trend: women using surgery to "tweak" the bits of their bodies they don't like after childbirth. Indeed, the so-called "mommy job" has become common in the US and these "makeovers" are becoming increasingly popular here.

McAllister had her surgery with Make Yourself Amazing, a company which promises "a life-changing experience that revitalises, rejuvenates but most of all reassures". It recommends breast surgery, tummy tucks and liposuction for the post-birth body - the aim is to erase all evidence of childbirth from a woman's body.

The Californian surgeon David A Stoker was one of the first to market the mummy makeover, offering an all-in plastic-surgery package that includes a breast lift, with or without implants, tummy tuck and liposuction. Women, says Stoker, need no longer feel "self-conscious or resentful about their appearance". Last year, the American Society of Plastic Surgeons performed more than 325,000 mummy jobs on women aged 20 to 39, up 11% on 2005.

The UK market is still small, but it is growing. A survey last October for the online bank Egg claimed that 0.2% of new British mothers had had surgery to get back their pre-baby bodies - but the real figure is likely to be higher. The number of cosmetic surgery procedures in the UK has doubled in the past two years, and surgeons report that breast surgery is increasingly popular with women who are unhappy with the way that breast feeding and pregnancy have altered their figures.

The mummy job is all about self-esteem, say fans. It is a misogynist pathologising of the post-pregnancy body, argue critics of the procedure. Diana Zuckerman, president of the US National Research Center for Women and Families, recently said that if marketing could turn the post-pregnancy body "into a socially unacceptable thing, think of how big your audience could be and how many surgeries you could sell them". In short, making women believe that their bodies look disgusting after childbirth is a marketing man's dream.

It is probably not difficult to achieve. On the parenting website Mumsnet, a popular thread about the post-baby body includes detailed and lengthy descriptions of inside-out belly buttons, loose skin, caesarean scar overhang, "diabolical stretchmarks" and handlebars sitting across hip bones, with everyone claiming that their disfigurement is the most hideous. "Does anyone know how this can be improved except for surgery?" asks one mother in desperation. A 2005 survey by Mother & Baby magazine found that 87% of new mothers were "positively unhappy" with their figures: 50% would "consider surgery"; 25% said they would "definitely have surgery".

The ravages of motherhood are mentioned as a factor in a quarter of the case studies featured in the most recent series of Channel 4's 10 Years Younger. The production company responsible for the programme, Maverick TV, posted a request on parenting forums which reads: "Mothers!! Has childbirth left your body looking like a deflated balloon? Have you lost the baby weight but not the wobble? Wish you could go from saggy tummy to yummy mummy? Then 10 Years Younger are here to help." Major surgery is always part of the process.

Rajiv Grover, a consultant plastic surgeon in Harley Street, lists "post-pregnancy surgery" as an option on his website and describes "women who want to get their bodies back after having children" as a major part of his client base. Breast surgery is common, he says: "What you're seeing now is women who are wanting not to be bigger but to have back what they've lost."

Also on Harley Street, Angelica Kavouni offers "cosmetic solutions for modern motherhood". A 40-year-old mother of two young children, she has had a mummy job herself in the form of a breast lift. "There are a few women who are lucky - maybe 10% to 15% - and their body shape returns to normal after childbirth," says Dr Kavouni. "Unfortunately with the rest of us - and I include myself in this - you are left with loose skin and your breasts appear droopy." She describes her breast surgery as "not an augmentation, just a small tidying-up". She now sees two to three clients a week who want the same, with or without tummy tuck.

"The type of women I tend to see have already lost a considerable amount of weight and are more or less back to their pre-pregnancy weight," she says. "They are the type who do yoga while they're pregnant, take care of their nutrition and find that although they have tried to take all the precautions, there are two problems: loose skin on the abdomen and breasts that never recovers. These women are not obsessed, they do not have operation after operation. They just want something very specific."

Post-pregnancy work is, she says, the "most rewarding" for a plastic surgeon because you are literally giving women their bodies back. "Of course, you don't have to have it done, you don't have to wear a bikini again - but why shouldn't you?"

Well, there's the money for starters. Cosmetic surgery starts at £1,000, though you can get it cheaper if you go abroad. Websites such as GorgeousGetaways.com offer Yummy Mummy Makeover packages in Kuala Lumpur: "Turn back the clock on your post-pregnancy body," it offers. Prices start from £4,000 for a three-week trip. "Together with a relaxing, tropical holiday with full childcare options, the packages ensure you get the results you are looking for and a peaceful, stress-free recovery." (How thoughtful of them to allow you to take your body-wrecking offspring with you.)

But there are other reasons, too. Mummy jobs are the next logical step in the battle to pretend that having a baby need not change you. Three years ago, New York magazine ran a report about women in Manhattan who maintained disordered, quasi-anorexic eating throughout pregnancy in order to stay as thin as possible. The ultimate goal is not to have to graduate into maternity wear at all. In America, mom-to-be clothes shops recently started stocking size zero for the first time. A survey at Johns Hopkins University in Baltimore indicated that 21% of pregnant women had engaged in "weight-restrictive" behaviour.

Tina Cassidy, the Boston-based author of Birth: A History, blames the celebrity effect: it is frequently alleged that some celebrity mothers have had their C-sections scheduled in the eighth month of pregnancy to avoid putting on weight in the last few weeks. "I had a friend who was joking with her obstetrician and he said, 'What about a tummy tuck like Britney?' At the time it was rumoured that Britney Spears had a tummy tuck on the heels of a caesarean section. This isn't technically possible, because the uterus is so large that you can't pull the skin too taut straight afterwards. It's not an official tummy tuck. But all the same, my friend's obstetrician said, 'I can make it so that things are pulled super-tight.'"

The worrying thing in America, she says, is that this "what baby?" surgery fad is eclipsing the real debate about women's lack of power when they are giving birth (a third of women in America have caesareans). "Women who have had a really powerful birth experience are enamoured by motherhood and feel that it completes them as a person," she says. "They don't dwell on the physical aspects. It's your badge of honour." What is wrong with our culture when it cannot celebrate women's bodies and what they can produce? "It's like nobody is supposed to get older and nobody is supposed to look any different when they've had a baby. Time is supposed to stand still for every woman's body. Why? My husband doesn't look like the same guy he was 10 years ago."

At least a backlash against this form of surgery has recently come from an unlikely source. In the first episode of the recently aired new series of the television drama Brothers and Sisters, Sarah Walker (played by Rachel Griffiths, real-life mother of two and non-beanpole) asks her husband if she should get a mummy job. He responds by ravishing her on top of the washing machine. Maybe all hope is not lost.

Marie Soudré-Richard, 32
Runs the internet children's fashion site Little Fashion Gallery, Fulham, London. Mother of Paul, aged two.

"Post-baby, there is a difference with my boobs - I have a very small chest. And to have very toned abs, I have to exercise twice as much as before. I only put on 14lbs when I was pregnant and I left the maternity ward in my normal jeans.

"It was a real effort not to put on weight - I lived on grilled chicken and broccoli. I wanted to recover my previous body as soon as possible. I loved being pregnant but as soon as I had the baby, I thought, my body needs to go back to normal. So I exercised - swimming or walking. It was all about being able to control my life and my body.

"I would love to have two or three children and if after the third one everything goes pear-shaped and my belly is horrible, I would consider surgery. Why not? I think in general in life when you have a problem and you find a way to fix it, then go for it. So many things change when you have children that for me it's all about controlling whatever you can - I needed to feel that I could control my weight, my life and how things are organised around me."

· This article was amended on Saturday January 5 2008. The name of the founder of the Little Fashion Gallery is Marie Soudré-Richard, not Marie-Soudre Richard as we said in the article above. This has been corrected.