An infant born to a mother with poorly controlled pregestational diabetes develops tachypnoea and grunting within hours of birth at 37 weeks. Chest radiograph shows ground-glass opacities. The underlying mechanism for this complication is:

• A Fetal hyperinsulinaemia accelerates lung maturation beyond gestational age
• B Fetal hyperinsulinaemia antagonizes the corticosteroid induction of surfactant synthesis ✓
• C Maternal hyperglycaemia suppresses fetal cortisol surge needed for labour
• D Chronic hypoxaemia causes secondary surfactant protein gene mutation

Explanation

Infants of diabetic mothers have delayed pulmonary maturation and an increased incidence of respiratory distress syndrome even at term. Fetal hyperinsulinaemia counteracts the glucocorticoid-mediated induction of phosphatidylcholine and surfactant synthesis in type II pneumocytes, shifting the lecithin to sphingomyelin maturation curve to the right. Option A is the reverse of the truth, and no genetic mutation is involved, which eliminates the remaining distractors.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.