A diet and exercise regime for high-risk obese pregnant women, whilst effective in promoting a healthy lifestyle, does not prevent gestational diabetes, a study has revealed.

Experts at Newcastle University have been part of research, published in the Lancet Diabetes and Endocrinology, which suggests that programmes promoting healthy behaviours are unlikely to be effective in preventing gestational diabetes in obese women; instead, resources should be directed towards better screening and treatment, including the use of a more stringent threshold for diagnosis.

The randomised UPBEAT study, funded by the National Institute for Health Research and led by King’s College London, recruited more than 1,500 women from eight inner-city antenatal services providing care to multi-ethnic populations of generally high socioeconomic deprivation across the UK.

Dr Ruth Bell (pictured), senior lecturer at Newcastle University's Institute of Health and Society and honorary NHS consultant, has been part of the research team. A total of eight universities and hospitals have been involved in the project.

She said: "Our study shows that an intensive diet and exercise regime alone cannot help reduce the risk of developing gestational diabetes in obese women.

"However, using a more stringent diagnostic test for gestational diabetes meant we picked up more cases. We believe the greater number of women treated as a result of this test may explain why our study found a lower than anticipated incidence of large-for-gestational-age delivery infants in all women.

“This has implications for the diagnosis of gestational diabetes in the UK as the National Institute for Health and Care Excellence have recently decided against adoption of World Health Organisation criteria to diagnose gestational diabetes and give treatment accordingly.

"The UPBEAT study provides a new and effective strategy to improve diet and physical activity in obese pregnant women adoptable in a UK healthcare setting. We are now following the mothers and children from this cohort to see whether changes in the mothers’ diet and activity are sustained and have an effect on their health and that of their offspring."

Obesity rates are highest in developed countries, affecting 25% of women in the UK and 34% of women in the US. Obesity is a risk factor for complications in pregnancy, especially gestational diabetes and large-for-gestational-age delivery. Previous studies have suggested that lifestyle intervention programmes might help reduce the risk of gestational diabetes in obese pregnant women, but this is first large-scale trial to test the effect of an intensive intervention in the UK and the world.

Half the women in the study were placed in a control group given standard antenatal care and advice, whilst the other half were assigned to eight, weekly, health trainer-led sessions. Participants were given a handbook with recommended foods, recipes and physical activity along with a DVD of an exercise regime safe for pregnancy, a pedometer and a log book for recording their weekly goals.

Exercise focused on increasing the amount of walking at a moderate intensity, and the women were advised to adopt a healthier diet by swapping carb-rich foods for those with a lower glycaemic index and limiting saturated fat intake.

All the women took a standard oral glucose tolerance test, but researchers used more stringent WHO-recommended criteria (also known as IADSPG criteria) to diagnose gestational diabetes and implement treatment accordingly.

Overall, 26% of all participants were diagnosed with gestational diabetes, but the study found no significant difference between the standard and intervention groups. Large-for-gestational-age delivery infants made up 9% of the whole trial cohort, but no difference was observed between standard and intervention groups.

However, the intervention led to other changes in the intervention group such a lower glycaemic load and fat intake along with higher levels of activity which were associated with reductions in pregnancy weight gain and reduced body fat.

Furthermore, researchers predicted that 17% of children would be large-for-gestational-age delivery, but found levels to be closer to normal population levels which they believe to be due to the greater number of women diagnosed and treated for gestational diabetes using the WHO guidelines.

published on: 10 July 2015