Gestational diabetes mellitus - GDM - is a form of diabetes which develops in pregnancy. Untreated GDM is associated with a higher incidence of pregnancy complications. Increased baby weight is common in GDM, leading to caesarean deliveries, birth injuries and trauma. GDM can also lead to high blood pressure and preeclampsia in the mother and development of type 2 diabetes later in the mother and the growing child. After GDM, 50% or more of mothers develop type 2 diabetes within 5-10 years and children have an 8-fold increased risk.