Large-for-gestational-age infant and infants of diabetic mothers — case

Case summary

A term male infant is born at 39 weeks to a 32-year-old multipara whose pregnancy was complicated by gestational diabetes diagnosed at 26 weeks and managed with metformin, with a high third-trimester HbA1c. Serial growth scans showed a rising estimated fetal weight above the 97th centile, prompting a planned delivery. Birthweight is 4400 g (above the 97th centile on an INTERGROWTH-21st chart). He is plump and plethoric with disproportionate shoulder and truncal adiposity and a palpable liver. At two hours of age he is jittery and a pre-feed glucose is low after a breastfeed. [3] [1]

Candidate tasks

1. Take a focused history and examine the infant; formulate a one-line problem representation. [3]
2. Outline your immediate and stepwise management of the neonatal complications. [1]
3. Counsel the parents about the diagnosis, the early plan and the long-term outlook. [7]

Focused history and examination

• Antenatal: maternal gestational diabetes, metformin management, high third-trimester HbA1c indicating poor control, rising estimated fetal weight above the 97th centile, polyhydramnios on the last scan, intrapartum glucose control, mode and indication for delivery. [4]
• Anthropometry: weight 4400 g (>97th centile), length and head circumference plotted on a gestation- and sex-specific chart; disproportionate truncal and shoulder adiposity and hepatomegaly confirming the hyperinsulinaemic phenotype. [5]
• Functional assessment: tone (jittery), colour (plethoric), temperature, respiratory effort, feeding. [1]
• Screen for complications and birth injury: clavicles and brachial plexus (normal Moro), facial nerve, heart and lungs, abdomen (palpable liver), skin (plethora). [3] [6]

One-line summary: "A 39-week male, birthweight 4400 g (>97th centile), infant of a poorly controlled gestational diabetic mother with a hyperinsulinaemic phenotype, now jittery with a low pre-feed glucose — IDM with early symptomatic hypoglycaemia." [3]

Immediate and stepwise management

• Warmth: dry, wrap, hat, warm room; aim for normothermia and skin-to-skin when stable. [1]
• Early feeding within the first hour, then at least 2–3 hourly; breast milk first to provide a steady exogenous glucose supply. [1]
• Scheduled pre-feed glucose monitoring through the first day; treat low glucose up the ladder: feed, then buccal 40% dextrose gel (200 mg/kg) with a feed and recheck, then intravenous 10% dextrose (2 mL/kg bolus then an escalating infusion) for persistent hypoglycaemia. [1] [2]
• Check a venous haematocrit for polycythaemia, serum calcium and magnesium, and a bilirubin as it develops; treat by thresholds and symptoms. [6]
• Observe for respiratory distress (RDS, transient tachypnoea, cardiomyopathy) and examine for birth injury. [3]
• Admit to transitional care or NICU as needed; plan discharge once thermally stable, glucose-stable on full enteral feeds, feeding competently, and with confident parents. [1]
• Long-term: growth monitoring, neurodevelopmental surveillance, and family education about childhood obesity and metabolic risk. [7]

Counselling the parents

• Explain clearly that their baby is large and jittery because maternal diabetes meant more glucose reached the baby in pregnancy, driving extra insulin that grew the baby large — and that the same extra insulin now drives the blood sugar down, which the team is actively treating. [4]
• Set immediate expectations: the team will focus on warmth, feeding and blood sugar in the first hours, and most babies stabilise quickly with feeding, dextrose gel and monitoring. [1]
• Be honest about the longer view: most infants recover fully from the early complications, but the family should know that offspring of diabetic pregnancies carry an increased risk of childhood obesity and later glucose problems — framed as a reason for healthy lifestyle and ongoing primary-care checks, not a foregone conclusion. [7]
• Invite questions and check understanding; offer written information and a follow-up contact. [7]