Women who eat a high fat diet during pregnancy may be increasing the risk that their child will develop heart problems in later life, research suggests.

Researchers found that rats fed a diet rich in lard - and similar to that provided by an over-reliance on fast food - were more likely to produce offspring that developed cardiovascular problems.

A diet high in animal fat eaten during pregnancy can permanently 'programme' abnormalities in the developing foetus. Dr Paul Taylor

The rats were fed either a standard breeding diet or a diet rich in animal fat before and during pregnancy.

Their offspring were fed a normal healthy diet, and were closely monitored for changes to their heart rate and blood pressure.

By middle age, both male and female offspring showed signs of blood vessel damage, with abnormal levels of fat in the blood.

High blood pressure was only recorded in female offspring.

Important implications

The researchers, who were funded by Tommy's, the baby charity, and the British Heart Foundation, said their findings have great implications for mums-to-be.

A diet that is too high in fat is a common problem among expectant mothers, particularly in the West.

Dr Paul Taylor, of Tommy's Maternal and Fetal Research Unit at St.Thomas' Hospital, London, said: "We have shown that a typical Western diet high in animal fat (e.g. 'fast food'), eaten during pregnancy can permanently "programme" metabolic and cardiovascular abnormalities in the developing foetus.

"Despite normal diet throughout life the adult offspring develop disease profiles typical of Western societies including abnormal blood lipids [fats], insulin resistance, and hypertension.

"If applicable to human pregnancy the "foetal programming" of adult disease by maternal dietary fat intake will have major implications both for our understanding of the causes of cardiovascular disease and for public health in general."

Dr Taylor said the results showed that female children might be more vulnerable than boys to the effects of too much fat in their mother's diet.

He said it was possible that a high fat diet led to cardiovascular problems by triggering the release of high levels of stress hormones in the developing foetus.

Stress hormones have been linked to problems with growth.

It is recommended that fat should account for no more than 30% of the calories contained in a daily diet.

The research focused on animal fats, not those derived from vegetable sources.

Pregnant women are advised to get their dietary fats from non-animal sources such as olive oil and vegetable margarine.