In a 10-year study of more than 21,000 pregnancies, published in the British Medical Journal (BMJ), women eating two to four servings a week were found to be 27% more likely to suffer diabetes in pregnancy.
Women who had five servings a week experienced a 50% increased risk of diabetes. However, study authors stressed the research did not prove potatoes were a cause of diabetes.
The experts, including from Harvard Medical School in Boston, said, according to PA: "Higher levels of potato consumption before pregnancy are associated with greater risk of (gestational diabetes), and substitution of potatoes with other vegetables, legumes, or whole grain foods might lower the risk."
Eating more than five servings a week had a 50% increased risk of diabetes
Dr Emily Burns, research communications manager at Diabetes UK, told HuffPost UK Parents: "This study does not prove that eating potatoes before pregnancy will increase a woman’s risk of developing gestational diabetes, but it does highlight a potential association between the two.
"However, as the researchers acknowledge, these results need to be investigated in a controlled trial setting before we can know more.
"What we do know is that women can significantly reduce their risk of developing gestational diabetes by managing their weight through eating a healthy, balanced diet and keeping active.
"We recommend that anyone who is concerned about their risk of developing gestational diabetes speaks to their healthcare professional."
In the new study, 854 women involved were affected by gestational diabetes.
The participants were asked about their total potato consumption in the previous year as part of a questionnaire.
One serving a week was found to be associated with an increased risk of diabetes by 20%, compared with women eating less than one serving a week, once body mass index (BMI) was taken into account.
One serving was considered to be one baked or boiled potato, 237ml of mashed potatoes or 113g fries.
When women replaced two servings of potatoes a week with other vegetables, pulses such as beans, lentils and peas, and whole grain foods, they experienced a 9% to 12% lower risk, according to the study authors.
One serving a week of potatoes may increase the risk of diabetes by 20%, according to the new study
The researchers made it clear potatoes could not cause diabetes, but they highlighted the potential negative effects of the food on blood sugar levels.
They said: "Though potatoes are rich in vitamin C, potassium, dietary fibre and some phytochemicals, unlike other vegetables they can have detrimental effects on glucose metabolism because they contain large amounts of rapidly absorbable starch."
The NHS states that up to 18% of women giving birth in England and Wales are affected by gestational diabetes.
It usually develops in the third trimester (after 28 weeks) and disappears after the baby is born.
Dr Louis Levy, head of nutrition science at Public Health England, said, according to PA: "As the authors acknowledge, it is not possible to show cause and effect from this study.
"The evidence tells us that we need to eat more starchy foods, such as potatoes, bread, pasta and rice, as well as fruit and vegetables to increase fibre consumption and protect bowel health.
"Our advice remains the same: base meals around a variety of starchy foods, including potatoes with the skin on, and choose wholegrain varieties where possible."
Janet Fyle, professional policy adviser at the Royal College of Midwives, said: "We cannot draw definitive conclusions from this research nor apply the findings to everyone.
"The key message from the research should be about varying the diet. Potatoes are a healthy food group. We need to tailor our messages to pregnant women so that they are able to have a well-balanced diet and not be put off eating them.
"We would encourage women who are pregnant or are thinking of becoming pregnant to have a healthy, varied diet including fresh fruit and vegetables, alongside taking folic acid supplements."