Eating lots of potatoes -- especially chips or crisps -- is linked to a higher risk for women of developing a type of diabetes that occurs during pregnancy, a study said Wednesday.

So-called gestational diabetes can have long-term health consequences for both mother and child, including a higher chance of heart disease and other forms of diabetes.

Potatoes -- consumed massively across the globe -- contain important nutrients, including vitamin C and potassium.

But compared to other vegetables and carbohydrates, they also contain extra starch, which is associated with a more rapid increase in blood sugar levels.

Generally speaking, diabetes occurs when the body is no longer able to make enough insulin, a hormone that prompts cells in the body to absorb sugar from the blood for energy and storage.

Up to now, the possible association between gestational diabetes and eating spuds had not been investigated.

To see if there was a link, researchers led by Cuilin Zhang at the National Institutes of Health in Rockville, Maryland used data from the Nurses' Health Study II, which has monitored more than 115,000 women since 1989.

Zhang and colleagues looked at the records for 15,632 women with no history of gestational diabetes or chronic disease who became pregnant between 1991 and 2001.

Of 21,693 single-foetus pregnancies, 854 -- some four percent -- developed gestational diabetes, according to the study published in the British Medical Journal.

The women were asked to report their potato consumption during the year previous to becoming pregnant, rating intake from "never or less than once a month" to "six portions per day".

This data was matched against medical records which showed whether they had developed gestational diabetes.

After taking other factors such as age and family history of diabetes into account, the study found a strong link with taters, especially fried and baked.

"Higher total potato consumption was significantly associated with an increased risk of gestational diabetes," the researchers concluded.

Doctors recommend changes in diet and exercise with the onset of gestational diabetes but in severe cases insulin treatment may be required.

The solution? Eat other vegetables and legumes -- a family including beans, peas and lentils -- instead of starchy spuds, the authors recommend.

Substituting two servings of potatoes a week with other vegetables or whole grain foods yielded an approximately 10 percent reduction in risk, they reported.

Despite the statistical evidence, the researchers say that a direct cause-and-effect link between eating potatoes and gestational diabetes "cannot be assumed."

But they noted that earlier studies have suggested that spuds can have a detrimental effect on blood sugar levels due to their high starch content.