Dieting while pregnant can lower your baby's IQ

Lack of nutrients interfer with the way brain cells connect in the unborn babies

Expectant mothers who diet during pregnancy are putting their babies at risk of low IQs and behavioural problems, scientists say.

A new study found that cutting back on vital nutrients and calories in the first half of pregnancy stunts the development of an unborn child's brain.

Although the study was carried out on animals, researchers says the same findings are likely to be true for women - and highlight the lifelong dangers to babies if their mothers don't eat healthily.

Author Dr Thomas McDonald said: 'This study is a further demonstration of the importance of good maternal health and diet.

'It supports the view that poor diets in pregnancy can alter development of foetal organs, in this case the brain, in ways that will have lifetime effects on offspring, potentially lowering IQ and predisposing to behavioural problems.'

Past studies have shown that severe diets, famines and food shortages during pregnancy can harm unborn babies.

But the new study looked at the sort of 'moderate dieting' typical of women in Britain and America.

The researchers compared two groups of baboon mothers at the a primate research centre in San Antonio.

One group was allowed to eat as much as they wanted during the first half of pregnancy - while the other group was fed 30 per cent less - 'a level of nutrition similar to what many prospective mothers' experience, the researchers said.

Cells did not divide as much as they should and connections between neurons were not made.

Lack of nutrients interfered with the way brain cells connected in the unborn babies and altered the expression of hundreds of genes - many involved in cell growth and development, the researchers report in the Proceedings of the National Academy of Sciences.

Dr McDonald said foetal nutrient deficiency was a special risk for both teenage mothers and women who get pregnant later in life.

Pregnant women are advised not to diet if they are pregnant

In teenage pregnancies, the developing foetus can be deprived of nutrients by the needs of the growing mother, he said.

And stiffer arteries in older women reduce blood flow to the womb, reducing the flow of nutrients to the growing baby.

The scientists called for more research into links between maternal diet and their children's risk of autism, depression and schizophrenia later in life.

The study also challenges the widely held view that mothers can protect their unborn babies from poor diets in pregnancy, he said.

The baboon's brain developmental stages are 'very close' to those of human fetuses, the researchers said.

Dr Peter Nathanielsz, of the University of Texas Health Science Centre in San Antonio said: 'This is a critical time window when many of the neurons as well as the supporting cells in the brain are born.'

Guidelines from the Royal College of Obstetricians and Gynaecologists state: 'There is little evidence of harm in the first half of pregnancy - but in the second half concerns arise.'

However, it still advises women not to diet if they find they are pregnant.

Dr Patrick O'Brien, consultant and spokesman for the Royal College of Obstetricians and Gynaecologists said the study might not apply to women.

'All the studies in humans have not suggested that moderate dieting in the first half of pregnancy causes any problems,' he said.

'Our guidance is unchanged - that pregnant women should eat a healthy mixed diet and should avoid dieting, but also avoid "eating for two",' he added.