CHILDREN whose mothers were obese during pregnancy are more likely to become overweight themselves because they develop a "fatty liver" in the womb, research has found.

It has long been known that overweight and obese women are more likely to give birth to heavy babies and that these infants are at greater risk of childhood obesity.

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However, research published in the Journal of Physiology has revealed for the first time how fat accumulates in the liver and metabolic pathways are disturbed in foetuses developing in obese mothers with diets high in sugar and fat.

While there is always some fat in the liver, when the liver fat increases above normal thresholds an individual is said to have a “fatty liver”.

Once they are born with this "fatty liver", these offspring are predisposed to childhood obesity and other chronic metabolic and cardiovascular diseases such as diabetes.

The researchers believe these complications "probably account for a significant proportion of the current epidemic of childhood obesity".

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More than half of all expectant mothers in Scotland are overweight or obese at the start of their pregnancy. The problem is more acute among older mothers.

Peter Nathanielsz, one of the lead investigators in the US study, said: “This research is important as throughout the world over 50 per cent of women of reproductive age are overweight or obese.

"Maternal obesity, combined with high fat, high sugar diets, makes it more likely that children will suffer from liver disease and face health problems such as obesity and heart disease later in life.

“It wasn’t until we saw the microscope slides for the staining of liver sections showing very high amounts of lipid in foetuses of obese mothers that we realised the dramatic impact of maternal obesity at such an early developmental time point."

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The study was carried out using obese pregnant monkeys. The liver cells of their developing foetuses were examined under a microscope to quantify the build up of stored fat and sugar.

Fatty liver build ups can be reversed, but if the accumulation persists the damage can lead to liver scarring and even liver cancer in later life.

The scientists believe significant changes may lie dormant, only to emerge under stress or when hormones begin to change with puberty or ageing.

The researchers now plan to now investigate metabolic and cardiovascular health of monkey offspring of obese mothers, including liver function, at regular intervals across their lifespan.

This will allow them to assess whether unwanted consequences of maternal obesity can pass across generations from mother to daughter to grandchildren.

They also plan to identify interventions that can reverse these unwanted changes.