A 2-day-old neonate, born at 33weeks of gestation and weighing 1.5kg, has 3 episodes of apnoea, each lasting for around 25 seconds and occurring after a feeding. During these episodes, there was bradycardia and extremities were cyanosed. Blood sugar is 50 mg/dL and serum calcium is normal. Which of the following is true regarding the apnoeic periods?
Due to seizures Secondary to hypoglycemia Due to an immature respiratory center Evidence of underlying pulmonary disease.