Low blood sugar - newborns
A low blood sugar level in newborn babies is also called neonatal hypoglycemia. It refers to low blood sugar (glucose) in the first few days after birth.
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 the baby also produces it in the liver.
Glucose level can drop if:
- There is too much insulin in the blood. 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 the glucose level up.
Neonatal hypoglycemia occurs when the newborn's glucose level causes symptoms or 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 level is more likely in infants with one or more of these risk factors:
- Born early, has a serious infection, or needed oxygen right after delivery
- Mother has diabetes (these infants are often larger than normal)
- Have slower than usual growth in the womb during pregnancy
- Are smaller or larger in size than normal for their gestational age
Infants with low blood sugar may not have symptoms. If your baby has one of the risk factors for low blood sugar, nurses in the hospital will check your baby's blood sugar level, even if there are no symptoms.
Also, blood sugar level is very often checked for babies with these symptoms:
- 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 level 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 for about 12 to 24 hours.
Other possible tests:
- Newborn screening for metabolic disorders, including blood and urine tests
Infants with a low blood sugar level will need to receive extra feedings with mother's milk or formula. Babies who are breast-fed may need to receive extra formula if the mother is not able to produce enough milk. (Hand expression and massage can help mothers express more milk.) Sometimes a sugar gel may be given by mouth temporarily if there is not enough milk.
The infant may need a sugar solution given through a vein (intravenously) if unable to eat by mouth, or if the blood sugar level is very low.
Treatment will be continued until the baby can maintain blood sugar level. This may take hours or days. 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 medicine to increase blood sugar level. In very rare cases, newborns with very severe hypoglycemia who do not improve with treatment may need surgery to remove part of the pancreas (to reduce insulin production).
The outlook is good for newborns who do not have symptoms, or who respond well to treatment. However, low blood sugar level can return in a small number of babies after treatment.
The condition is more likely to return when babies are taken off feedings given through a vein before they are fully ready to eat by mouth.
Babies with more severe symptoms are more likely to develop learning problems. This is more often true for babies who are at a lower-than-average weight or whose mother has diabetes.
Severe or persistent low blood sugar level may affect the baby's mental function. In rare cases, heart failure or seizures may occur. However, these problems may also be due to the underlying cause of the low blood sugar, rather than a result of the low blood sugar itself.
If you have diabetes during pregnancy, work with your provider to control your blood sugar level. Be sure that your newborn's blood sugar level is monitored after birth.
Devaskar SU, Garg M. Disorders of carbohydrate metabolism in the neonate. In: Martin RM, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 95.
Sperling MA. Hypoglycemia. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 92.
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, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.