Pregnant women who “eat for two” by increasing their consumption of fatty and sugary foods could be putting their unborn children at risk of obesity, research published today says.

Breast-feeding mothers who indulge in junk food could also increase their children’s chances of weight problems in later life.

Babies’ eating habits can be programmed even as they are in the womb by their mother’s own diets, the study, published in the British Journal of Nutrition, suggests.

Children who are exposed to “maternal junk food” in the womb or while breast-feeding may have more difficulty resisting unhealthy diet choices when they get older.Stephanie Bayol, of the Royal Veterinary College in London, said: “Our study has shown that eating large quantities of junk food when pregnant and breast-feeding could impair the normal control of appetite and promote an exacerbated taste for junk food in offspring. This could send offspring on the road to obesity and make the task of teaching healthy eating habits in children even more challenging.”

Dr Bayol’s team found that rats fed on a diet high in processed foods such as doughnuts and crisps during pregnancy and lactation gave birth to offspring that overate and had a preference for foods rich in fat, sugar and salt compared with rats on a regular diet.

Rats that were exposed in the womb to junk foods were born lighter than average, but quickly put on weight. Ten weeks after weaning, their body mass was 32 per cent higher for females and 22 per cent higher for males, compared with the offspring of normal diet mothers.

Dr Bayol’s team argues that similar trends could be expected in people.

Neil Stickland, co-author of the study, said: “The Government is trying to encourage healthier eating habits in schools, but our research shows that healthy eating habits need to start during the foetal and suckling life of an individual. Giving children better school dinners is very good, but more needs to be done to raise awareness in pregnant and breast-feeding women as well. Future mothers should be aware that pregnancy and lactation are not the time to overindulge on fatty-sugary treats on the misguided assumption that they are ‘eating for two’.”

Sue Macdonald, education research manager at the Royal College of Midwives, said that she was often surprised by how little many pregnant women knew about nutrition. But she said it was a myth that all women automatically overindulged when they were pregnant. They should equally avoid eating too little because of fears about consuming too much.

“Some women may think, ‘I’m eating for two’, but women we have surveyed can in fact be quite negative about their growing bodies and anxious about putting on weight. The message is to eat healthily, when you are hungry. Pregnant women should not take from this that they can never have a doughnut, just don’t have ten.”

Adam Balen, Professor of Reproductive Medicine at Leeds teaching hospitals, told The Times that the study reinforced the importance of maternal diet during pregnancy for the lifelong health of a child.

“We know more and more that early foetal influences can have a dramatic effect not just on child health but in the long term,” he said. “Our diet is bad as a nation and, although the advice at antenatal classes is to watch what you eat, general dietary information is not as good as it should be and so I’m not sure how often that message is taken on board. But mothers want the best for their children and most people I see in my clinics are hungry for information.”

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