A 28-year-old with pre-gestational Type 1 diabetes mellitus is booked at 8 weeks. Her HbA1c is 9.2%. Which fetal anomaly is most specifically associated with periconceptional hyperglycaemia in type 1 diabetes?
- A Ventricular septal defect
- B Neural tube defects
- C Caudal regression syndrome (sacral agenesis) ✓
- D Trisomy 21
Correct answer: C. Caudal regression syndrome (sacral agenesis)
Explanation
Caudal regression syndrome (sacral agenesis) is the anomaly most specifically and uniquely associated with maternal pre-gestational diabetes mellitus. While its absolute incidence is low, it is 200–400 times more common in infants of diabetic mothers compared to the general population, making it pathognomonic for this exposure. Neural tube defects (including anencephaly) and cardiac defects (VSD, transposition) are also increased in diabetic pregnancies but are not specific to diabetes. Trisomy 21 is not related to glycaemic control.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.