Twenty studies were evaluated to investigate the relationship between impaired glucose tolerance (definitions vary) during pregnancy and poor outcomes.  Two studies demonstrate the metabolic similarities between impaired glucose tolerance and gestational diabetes mellitus.  Twelve studies report increased risks of large for gestational age newborns and macrosomia in women with impaired glucose tolerance.  Additional research notes increased risks of preterm birth, perinatal morbidity and neonatal hypoglycemia.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.