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).