Neonatal hypoglycemia is low blood sugar (glucose) in the first few days after birth.

Babies need sugar (glucose) for energy. Most of that glucose is used by the brain.

The developing baby gets glucose from the mother through the placenta. After birth, the baby gets glucose by producing it in the liver and from food.

Glucose levels can drop if:

• There is too much of the hormone, insulin (hyperinsulinism). Insulin pulls glucose from the blood into the cells to be used for energy.
• There is not enough glycogen, the form in which glucose is stored in the body.
• The baby is not producing enough glucose.
• The baby’s body is using more glucose than is being produced.

Neonatal hypoglycemia occurs when the newborn’s glucose level is:

• Less than 30 mg/dL in the first 24 hours of life
• Less than 45 mg/dL after the first 24 hours of life

Hypoglycemia is the most common metabolic problem in newborns. It occurs in approximately 1 - 3 out of every 1,000 births.

Infants with the following risk factors are at high risk for neonatal hypoglycemia:

• Blood infection (sepsis)
• Endocrine disorders, such as low thyroid hormone production (hypothyroidism)
• Inborn errors of metabolism
• Intrauterine growth restriction
• Lack of oxygen shortly after birth
• Large for gestational age
• Mother with diabetes
• Mother who may have chorioamnionitis or an infection around the time of the baby's birth
• Premature birth
• Small for gestational age

Infants with hypoglycemia may not have symptoms. If they do occur, symptoms may include:

• Bluish-colored skin (cyanosis)
• Breathing problems
• Decreased muscle tone (hypotonia)
• Grunting
• Irritability
• Listlessness
• Nausea, vomiting
• Pale skin
• Pauses in breathing (apnea)
• Poor feeding
• Rapid breathing
• Problems with maintaining body heat
• Shakiness
• Sweating
• Tremors
• Seizures

Newborns at risk for hypoglycemia should have a blood test to measure blood sugar levels every few hours after birth. The health care provider should continue taking blood tests until the baby’s blood sugar level is normal.

Other possible tests:

• Newborn screening for metabolic disorders
• Urine tests

Infants with hypoglycemia may need to receive:

• Feeding with breast milk or formula within the first few hours after birth, either by mouth or through a tube inserted through the nose into the stomach (nasogastric gavage)
• Feeding with a sugar solution through a vein (intravenously) or by mouth (orally)

Treatment normally continues for a few days to 1 week.

If the low blood sugar continues, the baby may also receive medication to increase blood glucose levels (diazoxide) or to reduce insulin production (ocreotide).

In rare cases, newborns with very severe hypoglycemia who don’t improve with treatment may need surgery to remove part of the pancreas (to reduce insulin production).

The outlook is good for newborns who don’t have symptoms, or whose hypoglycemia gets better with treatment. However, hypoglycemia can return in a small percentage of babies after treatment.

The condition is more likely to return when babies are taken off intravenous feedings before they are fully ready to eat by mouth.

Babies with symptoms, especially those born at a low weight or to mothers with diabetes, are more likely to develop problems with learning.

Severe or long-term hypoglycemia may lead to brain damage, affecting normal mental function. Complications may include:

• Developmental delay
• Heart failure
• Mental retardation
• Seizures

Call your health care provider if your baby has symptoms of neonatal hypoglycemia.

If you have diabetes during pregnancy, work with your health care provider to control your blood sugar levels.

Stanley CA, Baker L. The causes of neonatal hypoglycemia. N Engl J Med. 1999 Apr 15;340(15):1200-1.

Newborn Nursery QI Committee. Guideline: Neonatal hypoglycemia: initial and follow up management. Portland (ME): The Barbara Bush Children's Hospital at Maine Medical Center; 2004 Jul. 4 p.

Cryer P. Glucose Homeostasis and Hypoglycemia. In: Kronenberg, HM, Melmed S, Polonsky KS, Larsen PR, eds. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders; 2008:chap 33.

Still BJ, Kliegman RM. The Endocrine System. In: Behrman RE, Kliegman RM, Jenson HB. Behrman: Nelson Textbook of Pediatrics. 17th ed. Philadelphia, Pa: Saunders; 2004:chap 96.

Updated by: Deirdre O’Reilly, MD, MPH, Neonatologist, Division of Newborn Medicine, Children’s Hospital Boston and Instructor in Pediatrics, Harvard Medical School, Boston, Massachusetts. Review provided by VeriMed Healthcare Network.