The former TV presenter Liz Fraser caused controversy in April 2006 when she confessed in Marie Claire that she had suffered from the eating disorder bulimia when pregnant with her second child. At the time, Fraser was promoting her first book: The Yummy Mummy's Survival Guide. “I thought that speaking out about this unspoken phenomenon would do a lot of good - getting it out in the open and making it easier for sufferers to ask for help,” she says.

In fact, Fraser received a mixed reaction: on the one hand dozens of letters from fellow sufferers thanked her for giving voice to their hidden suffering; on the other sections of the press accused her of hypocrisy for promoting the yummy mummy ideal.

Professor John Morgan, head of the Yorkshire Centre for Eating Disorders and Senior Lecturer at St George's University, London, says that Fraser is not alone. He estimates that 1 in 20 pregnant women may have an eating disorder (ED), sometimes referred to as “pregorexia”, and the figures may be higher still: “Women with eating disorders do not readily disclose their disorder to their obstetrician, and have been reported to ascribe their behaviours to symptoms of pregnancy, such as hyperemesis gravidarum [excessive morning sickness].”

According to some experts, images of svelte celebrity mums-to-be such as Nicoles Kidman and Richie with their “barely-there” bumps are inspiring expectant mothers to diet and exercise to excess to stay slim during pregnancy and speed the departure of those post-baby pounds. Some experts also believe that changes in shape and weight during pregnancy may exacerbate or rekindle latent anxieties and lead to a relapse of the disorder. One study even reported a worsening of symptoms in pregnancy in women with either anorexia nervosa or bulimia who were symptomatic at conception.

Fraser doesn't believe that her eating disorder had anything to do with wanting to be thin: “Pregnancy is a frightening and disorientating time and new motherhood is for many women an assault on identity and on everything you've ever known. Some women get depressed, others get eating disorders. Many get both.

“My eating disorder became my coping strategy - a habitual response to stress since I was a teenager that kicked in again when I felt vulnerable during pregnancy.”

Though fully recovered now, Fraser describes herself at that time as deeply confused and addicted to her cycle of bingeing and vomiting. “Like all addictive behaviours, it offered a brief escape from reality. It was like a fix: it gave me a huge high, I felt that I could achieve anything and then I'd feel wretched and each time the low was worse than the previous time.

“There was a rational part of me going: ‘What are you doing?' I felt stupid and selfish, a bad mother who didn't deserve children, but by then my entire being was tuned into this way of coping.”

“While most research findings conclude that ED symptoms decrease during pregnancy, this does not mean that they disappear,” explains Dr Nadia Micali, a researcher at the Institute of Psychiatry at King's College London who carried out a recent study involving more than 12,000 women in Britain. “Our results show that women continue to diet, use laxatives, exercise excessively and practise self-induced vomiting throughout pregnancy.”

And the findings make alarming reading. More than a quarter of women with a recent ED admitted to purging during pregnancy, during the first trimester, and 30 per cent had made themselves sick during the first five months of pregnancy.

Furthermore, about 30 per cent of women with a recent or past ED reported exercising excessively, while 10 per cent also reported dieting for weight loss at 32 weeks. Women with a recent ED had a significantly higher risk of using laxatives during the first 18 weeks of pregnancy.

But are pregnancy EDs becoming more common? “No studies have been carried out in this area,” says Micali. “However, we are seeing more and more pregnant women displaying ED behaviours such as bingeing and vomiting.”

Kate Dean experienced a dramatic intensification of her ED during pregnancy, losing more than 2½ stone of her pre-pregnancy weight before she reached her third trimester. Anorexic and bulimic since the age of 14, Kate was still symptomatic when she fell pregnant more than ten years later. “I had heard that anor- exics often go into remission during pregnancy and I naively thought that would happen to me.”

In fact, things just got worse. “I desperately wanted to eat well for my baby but didn't know how to eat normally. It was like I'd developed a phobia of it. I'd start each day saying: ‘Today I'll eat for my baby' but when faced with food I couldn't do it. Anything I did eat I'd throw up straight away. By the end I was eating one small meal a day then getting rid of it and exercising to excess right to the end of my pregnancy. I gave up diet pills and used laxatives on a couple of occasions. It wasn't that I didn't care about the effect of the ED of my baby, it's just that the ED was winning.”

For Dean it was all about the number on the scales: “I enjoyed being pregnant and I couldn't wait to be a mother but I just couldn't bear to see the number on the scales go up. It sounds incredibly vain but I'd been in the grip of an ED for so long that gaining weight, even though I was pregnant, was intolerable and terrifying.”

Low birth weight, prematurity and higher miscarriage rates have previously been reported in women with eating disorders. It is now believed that when it comes to anorexia nervosa during pregnancy, a “cycle of risk” may be at play, whereby poor nutrition during pregnancy in women with low weight because of an ED may lead to metabolic abnormalities and obstetric complications that then predispose the offspring to a later ED.

While most obstetricians ask women about their cigarette smoking and alcohol intake during pregnancy, fewer than 50 per cent of doctors ask about depression, body weight control and disordered eating. Research suggests that GPs consider a diagnosis of anorexia in only a third of true cases, while only 10 per cent of women with bulimia nervosa are identified, less than half of whom are referred for treatment.

“Eating behaviour should be routinely assessed in infertility clinics,” says Morgan. “The practice of ovulation induction is not recommended in women with active anorexia nervosa. Appropriate weight restoration is the treatment of choice for infertility in eating disorders, by which means fecundity is usually restored.”

But is the support available? When Kate Dean went to her GP at 12 weeks she was told that there were no facilities for ED sufferers in the area of Wales where she lives. Dean contacted beat, the leading UK charity for people with eating disorders and their families (www.b-eat.co.uk, 0845 6341414) and was told that the nearest ED unit was more than 150 miles away. She and her husband decided to pay privately for an assessment at 20 weeks at which Dean had severe anorexia diagnosed.

“The support I received was completely inadequate. Even after the assessment. I was given funding only for monthly sessions. I was seen only three times during my pregnancy, which just wasn't enough.” Pre-pregnancy counselling sessions and the first antenatal visit are good opportunities to screen for ED as women are perhaps more open to advice and help at these times. For this reason new guidelines from the National Institute for Health and Clinical Excellence recommend screening in vulnerable groups, but this has yet to be implemented.

“I've never understood why, when so many women have hang-ups about food, we all assume that pregnant women are somehow different,” says Liz Fraser. “We need to be so much more open about eating disorders in pregnancy. That way more women will feel empowered to ask for help.” But, as Kate Dean's experiences show, we also need to ensure that adequate help and support is available for those who request it.