The stars may be back to their pre-pregnancy sizes and on the red-carpet as much as two weeks after giving birth, but is it healthy?
The reality of celebrity baby weight
The four bikini-clad Victoria's Secret models featured in this month's American Elle magazine don't look like they've ever had a burger, let alone a baby. Tanned and toned, they pose seductively in the sand, free of stretch marks or C-section scars. This is despite the fact that three of the young "bodacious beauties" are new mothers. Adriana Lima had a daughter in November 2009 while Miranda Kerr and Doutzen Kroes gave birth to baby boys in January.
Ladies, this is your challenge, should you choose to accept it: gain the 11kg-16kg associated with a healthy pregnancy. Then drop it all off within two weeks of your child's birth, before you've been caught by the cameras.
Sound impossible? Unhealthy? It is. But that doesn't stop Hollywood celebrities - and, increasingly, regular women - from trying.
Hilda Hutcherson, an obstetrician-gynaecologist in New York, says more and more of the new mothers she sees seem surprised by how hard it is to lose their baby weight.
"They're mad about it," Hutcherson says. "They ask, 'why is it the stars can have their babies and a week later be walking on the red carpet - or doing the catwalk for Victoria's Secret - and here I am still in my maternity wear?'"
Part of the answer is that it's a lot easier for celebrities to get their bikini bodies back. They were in outstanding shape before the pregnancy, and they have access to personal trainers, nutritionists and chefs who assist them with their weight-loss goals. There are also more scandalous suggestions. Some stars limit their weight gain during pregnancy - which Hutcherson says is risky for the baby. There are rumours that others go doubly under the knife - combining a C-section with a tummy tuck, known as a "C-tuck."
The public's infatuation with pregnancy and motherhood began innocently enough. Twenty years ago, Demi Moore posed for Vanity Fair in what was then considered a provocative cover image - very pregnant, very uncovered. Since then, America seems to have grown more comfortable with pregnancy, and rallied around the cause - especially when motherhood is an expectant Claudia Schiffer in Vogue.
Dr Sarah Heaton, who works in a clinic north of Boston, knows exactly how prominent postnatal poses have become in the media. As part of her dissertation in psychology, she looked through People magazine's archives and counted the covers that feature pregnant or postnatal women. Ten years ago, it was one cover annually - now it's closer to four per year.
"I don't know where it's coming from and why it's exploded, but definitely the past decade has seen a major increase in how much it's portrayed in the media," Heaton said.
She added that part of the reason the postnatal stars look so good on the glossy covers is the lighting, make-up and clothing used in the photo-shoots. She called them "artificial images".
The dark side of the whole thing is that, according to Heaton's research, new mothers who read the magazines and watch the TV shows that portray postnatal celebrities have lower self-esteem than new mothers who aren't exposed to those images. She worries when she sees this in her clinic, as low self-esteem is a risk factor for postnatal depression.
But it's not the stars' fault, Heaton insists.
"They have more pressure on them than anyone," she says. "The problem is systemic."
The reality TV show star Kourtney Kardashian spoke out about the issue after she gave birth to her son, Mason, in December 2009. One week after the birth, OK magazine put her on the cover, looking sexy and svelte. The headline promised to disclose Kardashian's secrets to losing "10 lb in 10 days" in a "body after baby exclusive".
But it wasn't true. Kardashian used her Twitter account to correct the record:
"One of those weeklies got it wrong again...they didn't have an exclusive with me. And I gained 40 pounds while pregs, not 26...But thanks!"
In an interview with WWD later, Kardashian said the magazine had doctored the image to make it look like she had already lost all the weight, "which I have not". Later, her reality show showed her obsessing - working herself until exhausted and beating herself up because it was not happening fast enough - to be ready for her first photo shoot.
All this pressure to lose the pregnancy weight is misplaced, Hutcherson says. A new mother's focus is supposed to be on her baby - and if she's breastfeeding, she needs to be eating well. The doctor has four children of her own and knows firsthand the postnatal pressures and frustrations. But she insists mothers should not have a bikini body so soon after they've had a child.
"That's just not the case," Hutcherson said. "They have to give themselves time to get back into the jeans that they were in before they got pregnant."