Low blood sugar in newborns

What is neonatal hypoglycemia?

Neonatal hypoglycemia occurs when newborns have low blood sugar levels, typically in the first few days after birth. Babies rely on glucose, or sugar, as their primary energy source. They get glucose from breast milk or infant formula and also produce some in their liver. If not managed, low blood glucose can be dangerous and lead to health complications.

Symptoms of neonatal hypoglycemia

• Jitteriness
• Tremors
• Irritability with high-pitched cry
• Poor sucking and feeding
• Hypothermia (low body temperature)
• Bradycardia (slow heart rate) or tachycardia (rapid heart rate)
• Lethargy
• Poor alertness
• Tachypnea (rapid breathing)
• Apnea (prolonged pauses in breathing)
• Poor muscle tone
• Cyanosis (skin turns blue or purple in central areas of the body)
• Can occur without symptoms

Causes of neonatal hypoglycemia

• Reduced glucose supply,  history of intrauterine growth restriction, or babies who are small for gestational age.
• Impaired glucose production or availability after birth, common in infants of mothers with gestational diabetes or babies with metabolic disorders.
• Increased glucose use due to factors like perinatal stress, hypothermia, sepsis, or familial hyperinsulinism.
• Hormonal deficiencies, such as low levels of growth hormone or cortisol.
• Maternal medications taken during pregnancy, including some blood pressure medications, salicylates, or glucose-lowering drugs.
• Excessive insulin production, related to conditions like alloimmune hemolytic disease, meconium aspiration syndrome, polycythemia, or Beckwith-Wiedemann syndrome.

Treatment for neonatal hypoglycemia

The pediatrician’s primary treatment goal is to raise blood sugar levels. The first step is usually feeding the baby breast milk or infant formula right away or using an oral dextrose gel. If needed, intravenous glucose can be used. Further treatment may be required depending on the cause of the hypoglycemia.

How is neonatal hypoglycemia diagnosed?

Diagnosis is made by taking a blood sample to check the baby’s glucose levels. The specific glucose threshold for hypoglycemia depends on various factors, like symptoms and baby’s age (in hours post birth). Based on the baby’s symptoms, additional blood tests like serum electrolytes, blood counts, blood cultures, and hormone levels may also be ordered.

Normal glucose levels for newborns

A normal blood sugar level depends on whether the baby has symptoms and the infant's age in hours. Generally, levels of 70 mg/dL or higher are considered normal. For a baby with neonatal hypoglycemia, glucose levels below 40 mg/dL in the first 4 hours of life, or below 45 mg/dL between 4 and 24 hours, are considered low. Diagnostic thresholds may vary based on the baby’s symptoms.

Complications

• Seizures
• Neurocognitive developmental delays
• Cerebral Palsy
• Death