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]

SAQ 2 (10)

A 30-week fetus has an estimated fetal weight below the 3rd centile with absent end-diastolic flow on the umbilical artery Doppler. The obstetric team is weighing surveillance against delivery. [4] [5]

1. Distinguish early-onset from late-onset FGR and explain why the distinction changes management. (3) [2]
2. Summarise what the TRUFFLE trial taught about delivery timing in early-onset FGR before 32 weeks. (4) [5]
3. Outline the long-term outcomes families should be counselled about, and how you would structure follow-up. (3) [6]

Model answer

1. Early-onset FGR (before 32 weeks) is rare, severe, driven by serious placental failure, and monitored with Doppler and computerised CTG; late-onset FGR (32 weeks and beyond) is commoner, lower in absolute mortality but carries a real stillbirth risk, and is monitored mainly with growth and the cerebroplacental ratio. The distinction changes surveillance intensity, the tests used and the delivery thresholds. [2]
2. TRUFFLE showed that, before 32 weeks, delivery timed to late computerised CTG deterioration and ductus venosus change gave the best 2-year neurodevelopmental outcomes, rather than delivery driven by umbilical artery Doppler alone. The GRIT–TRUFFLE comparison confirmed that watchful, surveillance-driven delivery did not worsen long-term outcomes compared with earlier delivery. [5]
3. Counsel families about a guarded but improvable prognosis in severe early FGR, with risks of mortality, neurodevelopmental impairment and cerebral palsy in the most severe cases, and recognised lifelong cardiovascular and metabolic risk from fetal reprogramming. Structure follow-up as growth monitoring, neurodevelopmental surveillance, vision and hearing checks if very preterm, and ongoing family support and counselling. [6]