Paediatrics: Large for gestational age

Large for gestational age

Defined as birth weight >90th centile for gestational age.

Causes

• Most frequently constitutional, i.e. large parents.
• Infant of a mother with diabetes mellitus.
• Foetal hyperinsulinism, pancreatic islet cell hyperplasia.
• Hydrops foetalis.
• Beckwith–Wiedemann syndrome.

Complication

• Perinatal asphyxia, nerve palsies, shoulder dystocia, fractures.
• Hypoglycaemia, especially if due to maternal diabetes or in BWS.
• Problems associated with the underlying cause of LGA.

Management

• Careful obstetric management to prevent obstetric complications.
• Examine for associated features, e.g. BWS or signs of birth injury.
• Prevent hypoglycaemia.

Prognosis 

Generally excellent (unless hydrops foetalis) if managed well.

Infant of a mother with diabetes mellitus

Pathophysiology

Maternal hyperglycaemia l ‘rise’ foetal glucose l I foetal insulin secretion (antenatally has growth hormone function) l macrosomia, organomegaly, and polycythaemia. Rarely, the maternal vascular disease results in foetal IUGR.

Associated complications

• 2–4 risk of congenital abnormalities: caudal regression syndrome (sacral and femoral agenesis or hypoplasia); transient hypertrophic cardiomyopathy; small left colon syndrome; neural tube defects.
• Obstetric complications (see Complications): increased risk of spontaneous miscarriage, intrauterine foetal death, and prematurity.
• Hypoglycaemia: generally resolves as serum insulin level falls.
• Respiratory disease: respiratory distress.
• Polycythaemia. Risk of secondary thrombosis (e.g. renal vein).
• Exaggerated physiological jaundice.
• Hypocalcaemia and hypomagnesaemia.

Management

Optimize maternal glycaemic control during pregnancy.

Prognosis

• Normoglycaemia occurs within 48hr in the vast majority.
• 7 x increased risk of diabetes mellitus in later life.
• Increased risk of later obesity and, possibly, poor development.