Women who regularly eat fried food before becoming pregnant are at a much higher risk of developing gestational diabetes, a new study has found.

Gestational diabetes is a type of diabetes that develops during pregnancy - most often in the second or third trimester. It usually disappears after the baby is born, although women who develop it are at an increased risk of developing diabetes later on.

It can lead to complications for the child, such as increased birth weight and jaundice. If left untreated, it can cause other complications, including stillbirth.

US researchers set out to investigate any links between the consumption of fried foods before conception and the risk of developing gestational diabetes. They used data from an ongoing study involving over 116,000 women aged between 25 and 44.

They focused on 15,027 women who gave birth to over 21,000 single babies. All were regularly asked about general health and diet, including their consumption of fried foods, such as fried chicken, fried fish and French fries.

During a 10-year follow-up period, almost 850 cases of gestational diabetes were diagnosed.

The study found that those who consumed fried foods on a weekly basis prior to becoming pregnant had an increased risk of developing gestational diabetes. The more often they consumed these foods, the higher the risk.

Those who consumed fried foods between four and six times per week had a 14% increased risk. However, among those who consumed these foods seven or more times per week, their risk jumped by 88%.

The researchers said that the reason for this may be down to what occurs during the frying process.

"Frying deteriorates oils through the processes of oxidation and hydrogenation, leading to an increase in the absorption of oil degradation products by the foods being fried, and also a loss of unsaturated fatty acids such as linoleic and linolenic acids, and an increase in the corresponding trans fatty acids such as trans-linoleic acids and trans-linolenic acids," they noted.

Trans fats are artificially produced fats that are used in thousands of processed foods, from fried food to biscuits and ready-meals. They have already been linked to an increased risk of heart disease.

The researchers also noted that frying can result in much higher levels of ‘dietary advanced glycation end products (AGEs)'.

"Recently, AGEs have been implicated in insulin resistance, pancreatic beta-cell damage, and diabetes, partly because they promote oxidative stress and inflammation. Moreover, intervention studies with a diet low in AGEs have shown significantly improved insulin sensitivity, reduced oxidant stress, and alleviated inflammation," they pointed out.

Meanwhile, the researchers from the US National Institutes of Health also found that when studied separately, fried food consumption outside of the home was found to have stronger links with gestational diabetes than fried foods consumed within the home.

"Deterioration of oils during frying is more profound when the oils are reused, a practice more common away from home than at home. This may partly explain why we observed a stronger association of gestational diabetes risk with fried foods consumed away from home than fried foods consumed at home," they noted.

They concluded that frequent fried food consumption ‘was significantly and positively associated with the risk of incident gestational diabetes'.

"Our study indicates potential benefits of limiting fried food consumption in the prevention of gestational diabetes in women of reproductive age. Further studies are warranted to confirm our findings and to discover the underlying mechanisms," they added.

Details of these findings are published in the journal, Diabetologia.