In accordance with the Danish routine screening procedure for GDM [15], nulliparous pregnant women with pre-pregnancy BMI > 27 kg/m2 (BMI calculated as weight in kilos divided by height2 in meters2), family history of diabetes, or polyhydramnios were invited to have a 75 g oral glucose tolerance test, and GDM was diagnosed if the two hour blood glucose level was above 9.0 mmol/L