Gestational diabetes mellitus (GDM) is one of the most common medical conditions in pregnancy, and the prevalence is growing with increasing rates of women of advanced age becoming pregnant and the increasing prevalence of maternal obesity and inactivity. GDM is associated with an increased risk of maternal and infant short- and long-term ill-health. There is a positive linear association between increasing maternal glucose at oral glucose tolerance testing and risk of important perinatal outcomes, including cesarean section, large for gestational age, and infant adiposity. A "step-up" approach, where diet and lifestyle information is provided followed by pharmacological interventions as required to control and reduce hyperglycemia, is effective at reducing the risk of macrosomia, but treatment of GDM will increase demand on health services. There is limited evidence to suggest which identification strategy is best or what thresholds should be used to diagnose GDM or what the effects of different diagnostic strategies have on short- or long-term maternal and offspring outcomes. Trials of interventions in pregnancy aimed at preventing GDM have not demonstrated a benefit; therefore, trials are needed to evaluate interventions aimed at optimizing the health of all women of childbearing age, outside of pregnancy. A consistent, evidence-based, sustained approach to supporting women to live healthily, including the achievement of a normal body mass index before and after pregnancy, is urgently needed.
Keywords: adverse perinatal outcomes; gestational diabetes; glucose threshold criteria; screening.