Causes

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

The baby gets glucose from the mother through the placenta before birth. After birth, the baby gets glucose from the mother through her milk or from formula, and also produces it in the liver.

Glucose levels can drop if:

• There is too much insulin in the blood (hyperinsulinism). Insulin is a hormone that pulls glucose from the blood.
• The baby is not producing enough glucose.
• The baby's body is using more glucose than is being produced.
• The baby is not able to feed enough to keep glucose levels up.

Neonatal hypoglycemia occurs when the newborn’s glucose level is below the level considered safe for the baby's age. It occurs in about 1 to 3 out of every 1,000 births.

Low blood sugar levels are more likely in infants:

• Who were born early, have a serious infection, or needed oxygen right after delivery
• Whose mother has diabetes (these infants are often larger than normal)
• With low thyroid hormone levels (hypothyroidism)
• Who have certain rare genetic disorders
• Who have poor growth in the womb during pregnancy
• Who are smaller in size than normal for their gestational age

Symptoms

Infants with low blood sugar may not have symptoms. After birth, nurses in the hospital will check your baby's blood sugar levels, even if there are no symptoms.

If they do occur, symptoms may include:

• Bluish-colored or pale skin
• Breathing problems, such as pauses in breathing (apnea), rapid breathing, or a grunting sound
• Irritability or listlessness
• Loose or floppy muscles
• Poor feeding or vomiting
• Problems keeping the body warm
• Tremors, shakiness, sweating, or seizures

Exams and Tests

Newborns at risk for hypoglycemia should have a blood test to measure blood sugar levels every few hours after birth. This will be done using a heel stick. The health care provider should continue taking blood tests until the baby’s glucose level stays normal.

Other possible tests:

• Newborn screening for metabolic disorders
• Urine tests

Treatment

Infants with low blood sugar levels will need to receive extra feedings with breast milk or formula. Babies who are breast-fed may need to receive extra formula until the mother is able to produce enough breast milk.

The baby may need a sugar solution given through a vein (intravenously) if he or she is unable to eat by mouth, or if the blood sugar is very low.

Treatment will be continued for a few hours or days to a week, or until the baby can maintain blood sugar levels. Infants who were born early, have an infection, or were born at a low weight may need to be treated for a longer period of time.

If the low blood sugar continues, in rare cases the baby may also receive medication to increase blood sugar levels. In very 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).

Outlook (Prognosis)

The outlook is good for newborns who do not have symptoms or who respond well to treatment. However, low blood sugar levels can return in a small number 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 more severe symptoms are more likely to develop problems with learning. This is especially true for babies who are at a lower-than-average weight or whose mother has diabetes.

Possible Complications

Severe or persistent low blood sugar levels may affect the baby's mental function. In rare cases, heart failure or seizures may occur. 

Prevention

If you have diabetes during pregnancy, work with your health care provider to control your blood sugar levels. Be sure that your newborn's blood sugar levels are monitored after birth.

Alternative Names

References

Adamkin DJ and Committee on Fetus and Newborn. American Academy of Pediatrics clinical report - postnatal glucose homeostasis and late-preterm and term infants. Pediatrics. 2011;127:575-579.

Updated: 4/14/2012

Reviewed by: Kimberly G. Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.