It is controversial whether maternal hyperglycemia less severe than that in diabetes
mellitus is associated with increased risks of adverse pregnancy outcomes.
A total of 25,505 pregnant women at 15 centers in nine countries underwent 75-g oral
glucose-tolerance testing at 24 to 32 weeks of gestation. Data remained blinded if
the fasting plasma glucose level was 105 mg per deciliter (5.8 mmol per liter) or
less and the 2-hour plasma glucose level was 200 mg per deciliter (11.1 mmol per liter)
or less. Primary outcomes were birth weight above the 90th percentile for gestational
age, primary cesarean delivery, clinically diagnosed neonatal hypoglycemia, and cord-blood
serum C-peptide level above the 90th percentile. Secondary outcomes were delivery
before 37 weeks of gestation, shoulder dystocia or birth injury, need for intensive
neonatal care, hyperbilirubinemia, and preeclampsia.
For the 23,316 participants with blinded data, we calculated adjusted odds ratios
for adverse pregnancy outcomes associated with an increase in the fasting plasma glucose
level of 1 SD (6.9 mg per deciliter [0.4 mmol per liter]), an increase in the 1-hour
plasma glucose level of 1 SD (30.9 mg per deciliter [1.7 mmol per liter]), and an
increase in the 2-hour plasma glucose level of 1 SD (23.5 mg per deciliter [1.3 mmol
per liter]). For birth weight above the 90th percentile, the odds ratios were 1.38
(95% confidence interval [CI], 1.32 to 1.44), 1.46 (1.39 to 1.53), and 1.38 (1.32
to 1.44), respectively; for cord-blood serum C-peptide level above the 90th percentile,
1.55 (95% CI, 1.47 to 1.64), 1.46 (1.38 to 1.54), and 1.37 (1.30 to 1.44); for primary
cesarean delivery, 1.11 (95% CI, 1.06 to 1.15), 1.10 (1.06 to 1.15), and 1.08 (1.03
to 1.12); and for neonatal hypoglycemia, 1.08 (95% CI, 0.98 to 1.19), 1.13 (1.03 to
1.26), and 1.10 (1.00 to 1.12). There were no obvious thresholds at which risks increased.
Significant associations were also observed for secondary outcomes, although these
tended to be weaker.
Our results indicate strong, continuous associations of maternal glucose levels below
those diagnostic of diabetes with increased birth weight and increased cord-blood
serum C-peptide levels.
Copyright 2008 Massachusetts Medical Society.