Hypoglycemia is defined as an abnormally low blood glucose level. In neonates, it is typically considered when blood glucose levels fall below 40 mg/dL (2.2 mmol/L). It can be caused by various factors such as prematurity, intrauterine growth restriction (IUGR), or maternal diabetes. Symptoms of hypoglycemia can include jitteriness, lethargy, poor feeding, and in severe cases, seizures.