The primary outcome was the prevalence of the combined
diagnoses of decreased gestational glucose tolerance and
gestational diabetes mellitus. This was defined in accordance
with previous published practice.18–21 Women underwent,
on consecutive days, a 75 g fasting 2-h glucose tolerance test
(GTT) and then a 100 g fasting 3-h GTT. This second test
was part of a different substudy. For the purposes of the
trial, the primary outcome depended upon the 75 g GTT
meeting WHO criteria.20 This meant the 2-h plasma glucose
result was > 6.6 mmol ⁄L to meet the criteria of decreased
gestational glucose tolerance or > 7.7 mmol ⁄L to meet the
criteria of gestational diabetes mellitus.
The secondary outcomes were as follows:
1 weight gain in pregnancy defined as the difference
between the booking weight and weight at the onset of
labour and
2 birthweight, as measured by the attending midwife
immediately following birth on neonatal scales which had
been calibrated at the start of the study and every month
during the study period.