However, a large multicentre randomised controlledtrial (Poston et al, 2015) hypothesised that a combinedintervention of a low glycaemic diet and physical exercisemay have an effect on maternal weight gain in obesewomen during pregnancy, reducing the incidenceof GDM and large for gestational age or macrosomic babies. Unfortunately, the results of this trial indicated that the combination of diet and exercise did not have any significant effects on outcomes for obese pregnant mothers and their babies when compared to obese women following routine antenatal care, and although diet and physical activity improved, there was no effect on the incidence of GDM or macrosomic babies in the intervention group. It therefore appears that other factors may have an impact on incidence of GDM and maternal and neonatal outcomes for obese women in pregnancy.