Research shows women with gestational diabetes who control it with a healthy diet without insulin are at no greater risk of giving birth to a big baby.

A healthy diet alone can control gestational diabetes and doesn't put the mother at greater risk of having a big baby, an Australian study has found.

Dr Fatima Vally led the study at the Royal Women's Hospital and says the "exciting" findings - published in the Journal of Pregnancy - should provide reassurance to the one in 10 pregnant women who will develop diabetes during their pregnancy.

"For women who control their diabetes with diet, we found that they didn't have bigger babies compared to women without the condition," said Dr Vally.

Women with gestational diabetes can face an up to 50 per cent increased risk of having a large baby, which can cause serious complications such as injury to the baby and mother during delivery.

"We know big babies may have a greater tendency to get stuck in labour which can cause injury to both the baby and mother, so it's a really important outcome to look at," Dr Vally said.

Babies can also face a higher risk of low blood sugar levels and needing special treatment after birth.

However, a study involving 202 women with gestational diabetes conducted at the Royal Women's Hospital has shown with adequate dietary advice and regular blood glucose monitoring those risks are minimised.

On average, these women gave birth to slightly smaller babies compared to healthy pregnant women in the control group.

"There is strong evidence of relatively small mean differences in birth weight and EGA (estimated gestational age) with and without gestational diabetes," the authors wrote.

Dr Vally says the results, potentially, mean less hospital visits during pregnancy for women with gestational diabetes.

"At the moment women who have gestational diabetes come to hospital once a fortnight for a visit with an obstetric doctor as well as their visits with the dietician, the diabetes nurse and educators," she told AAP.

"However if their diabetes is really well controlled and they are not at risk of having bigger baby they could continue to see the midwife or GP that they normally see rather than need to come in hospital for more third trimester ultrasounds."

Senior author and Head of the Women's Diabetes in Pregnancy Clinic Dr Tom Cade says the research shows the dietician may be the most important health professional for these women.

"We can now make changes in our clinical approach, which, for our patients, means fewer inductions and visits with obstetricians, more opportunity to be cared for by their midwives and less fear about their condition," Dr Cade said.

However, he did note that this approach would only be suitable for women who are regularly testing their blood glucose and who meet their targets with suitable dietary modification.