Fetal growth restriction and small-for-gestational-age infant — formative SAQs

SAQ 1 (10)

A 37-week male infant is born weighing 2150 g (below the 3rd centile for gestation and sex on an INTERGROWTH-21st chart). The pregnancy was complicated by pre-eclampsia; antenatal umbilical artery Doppler showed absent end-diastolic flow. He is wasted, with a disproportionately large head and loose dry skin. At two hours of age he is cool (35.6 °C) and a pre-feed glucose is low despite a breastfeed. ^{[1] [4]}

1. Define the key terms small-for-gestational-age (SGA) and fetal growth restriction (FGR), and explain why they overlap but are not synonymous. (3) ^[1]
2. Outline the four neonatal complications you should most actively anticipate and pre-empt in this infant. (3) ^[8]
3. Describe your stepwise management of his hypoglycaemia. (4) ^[8]

Model answer

1. SGA is a size descriptor: birthweight or estimated fetal weight below the 10th centile (severe below the 3rd) for gestation and sex on a standard chart. FGR is a pathological failure to reach genetic growth potential, usually from placental insufficiency. They overlap because many FGR infants are SGA, but a constitutionally small infant is healthy and not growth-restricted, and a growth-restricted fetus may not yet be below the 10th centile if its velocity has only just fallen. ^{[1] [2]}
2. The four complications to pre-empt are hypothermia (low fat stores), hypoglycaemia (depleted glycogen), polycythaemia/hyperviscosity (chronic hypoxia-driven erythropoietin) and feeding difficulty (starved gut). ^[8]
3. Warm the infant and feed within the first hour; recheck pre-feed glucose on a schedule; if low after a feed, give buccal 40% dextrose gel (200 mg/kg) with a feed and recheck; escalate to an intravenous 10% dextrose bolus then an escalating infusion for persistent hypoglycaemia; involve senior/neonatal team and treat any underlying cause. ^[8]