Which medication is responsible for neonatal hypoglycemia?

• A. Warfarin
• B. Simvastatin
• C. Tolbutamide
• D. Methimazole

Answer: (C)

Exposure of the fetus to drugs that boost insulin release can lead to neonatal hypoglycemia after birth. Tolbutamide is a first-generation sulfonylurea that crosses the placenta and stimulates the fetal pancreatic beta cells to secrete insulin. After birth, the newborn loses the maternal glucose supply but may still have high insulin levels, causing their blood glucose to drop. The other drugs listed don’t act by increasing fetal insulin production: warfarin causes fetal bleeding risk, simvastatin is teratogenic, and methimazole can affect fetal thyroid development but does not commonly cause neonatal hypoglycemia. So tolbutamide best explains neonatal hypoglycemia.