Maternal characteristics
We recorded information on maternal age, racial origin (White, Black, Asian and mixed), medical history, parity (parous and nulliparous if there was no previous pregnancy with delivery at ≥24 weeks´ gestation). Weight and height were measured and body mass index calculated at their clinical visit. The diagnosis of GDM was made by performing the two-step approach at 24-28 weeks’ gestation recommended by NICE guidelines; a result from the 75 mg oral glucose tolerance test (OGTT) was considered to be positive if the fasting plasma glucose was ≥5.6 mmol/L or the 2-hour plasma glucose level was ≥7.8 mmol/ (7). Management of GDM was based on target glucose ranges and insulin or metformin were used when dietary management failed. Glycemic control was assessed by home self-monitoring and use of a glycometer for daily measurement of the fasting and 1-hour post-prandial capillary blood glucose level; the normal values for fasting blood glucose are 3.9-5.3 mmol/L and for 1-hour post-prandial blood glucose are 5.0-7.8 mmol/L. The records of each patient were reviewed by an endocrinologist at the time of the clinical visit and based on the results the method and dose of treatment were adjusted appropriately to ensure good glycemic control. Postnatally, all patients with GDM were offered a fasting plasma glucose test 6-13 weeks after birth to exclude the presence of diabetes mellitus. Data on pregnancy outcome were collected from hospital delivery records or the general medical practitioners. Birth weight for gestational age was converted to a Z-score based on the Fetal Medicine Foundation fetal and neonatal weight chart (8).