Gestational diabetes

Gestational diabetes is the second most common medical disorder complicating pregnancy (after hypertension), affecting around 4% of pregnancies.

Diabetes mellitus may be a pre-existing problem or develop during pregnancy, gestational diabetes. It complicates up to 1 in 20 pregnancies. NICE estimates the following breakdown:

• 87.5% have gestational diabetes
• 7.5% have type 1 diabetes
• 5% have type 2 diabetes

Risk factors for gestational diabetes

• BMI of > 30 kg/m²
• previous macrosomic baby weighing 4.5 kg or above
• previous gestational diabetes
• first-degree relative with diabetes
• family origin with a high prevalence of diabetes (South Asian, black Caribbean and Middle Eastern)
• unexplained stillbirth in a previous pregnancy

Complications

Maternal complications

• polyhydramnios - 25%, possibly due to fetal polyuria
• preterm labour - 15%, associated with polyhydramnios

Neonatal complications

• macrosomia (although diabetes may also cause small for gestational age babies)
• hypoglycaemia (secondary to beta cell hyperplasia)