The findings of our study highlight a higher prevalence of GDM among women who are overweight or obese than has been previously reported, with significant public health implications given the worldwide health burden associated with obesity among women of reproductive age. The reduction in foetal macrosomia we observed in women diagnosed with GDM likely reflects a treatment effect, consistent with the findings of the LIMIT study where macrosomia was reduced by an antenatal lifestyle intervention in women with increased BMI, regardless of GDM status [31]. Our data demonstrated an increased rate of LGA infants in women who are obese independent of GDM, which is attributable to the shared metabolic characteristics of these two conditions. These findings suggest that greater emphasis should be placed on increased maternal BMI as a risk factor for LGA, and as a target for lifestyle intervention to reduce the risk of foetal macrosomia. Previous studies relating to hyperglycaemia in pregnancy have been conducted in women with untreated GDM [30] and [35]. The LIMIT study provided universal screening for diagnosis of GDM, and treatment was initiated routinely, reflecting current clinical practice. This pragmatic approach allows application of our results to everyday obstetric practice and clinical risk assessment.