An Overview of Neonatal Hypoglycemia

Neonatal hypoglycemia is when a newborn’s blood glucose (sugar) is too low. Glucose is the main fuel source for the body and brain. In a newborn, low blood sugar has many causes.

It can also cause problems, including breathing and feeding issues. The condition is treatable, but if not detected, it could be fatal, especially if an underlying condition is to blame.  

Prevalence

Neonatal hypoglycemia affects up to about 4 per 1,000 full-term births according to some studies. It is usually associated with risk factors, including the mother and baby's health, the baby's size, and gestational age at delivery (how many weeks of pregnancy when the baby is born). In fact, the incidence in high-risk newborns can be as high as 30 percent.

Research reported in The Journal of Pediatrics finds more than half of newborns with risk factors could become hypoglycemic. 

During the study, blood glucose testing was done within 48 hours after birth for newborns who had risk factors, with the following results:

• A little more than half of the newborns were hypoglycemic.
• 19 percent had severe hypoglycemia.
• 19 percent had more than one episode of hypoglycemia.

The researchers concluded that neonatal hypoglycemia is common for newborns with risk factors, and multiple risk factors put the newborns at a higher risk. The researchers did not make any conclusions about long-term outcomes.

Causes and Risk Factors

Babies get glucose from their mothers through the placenta before they are born. After birth, their sources of glucose are breast milk and formula. Glucose is also produced in the liver. Blood sugar may drop if the baby is not able to eat enough.

Other causes of neonatal low low blood sugar include the baby not producing enough glucose, using too much glucose, or making too much insulin (a hormone that pulls glucose from the blood).

Some newborns have certain risk factors that make them more likely to develop neonatal hypoglycemia. 

These may include:

• Maternal hypertension (high blood pressure)
• Baby born too early
• Maternal or neonatal infection
• Baby needs oxygen after delivery
• Mother with diabetes
• Slow growth of the baby while in the womb
• High or low birth weight

Your healthcare provider will test your baby's glucose levels with routine tests, but additional testing may be needed if your baby is at risk of having low glucose.

Symptoms

In newborns, a blood glucose level of less than 30 mg/dL (milligrams per deciliter) in the first 24 hours of life and less than 45 mg/dL after that constitutes neonatal hypoglycemia. The effects of neonatal hypoglycemia are not always obvious in a newborn, and the symptoms can vary.  

Symptoms may include:

• Bluish or pale skin color
• Apnea (breathing pauses) or rapid breathing
• Hypothermia (low body temperature)
• Jitteriness, grunting, and/or irritability
• Poor feeding or vomiting
• Lethargy (general feeling of unwellness)
• Tremors or seizures

If your newborn is experiencing any of these symptoms, talk to your healthcare providers about it right away. 

Complications

In severe cases, neonatal hypoglycemia may affect the heart or brain and can cause seizures. However, this is rare, and newborns who continue to have low blood sugar usually have an underlying medical condition that needs treatment.

Diagnosis

Diagnosis of neonatal hypoglycemia is done with a serum glucose test. It is a blood test that measures blood sugar in a newborn using a heel stick. This is an easy and minimally invasive way to do blood work for newborns, where blood is drawn from the heel of the foot.

If blood sugar is low, the healthcare provider will continue to monitor it to determine if treatment is necessary. Sometimes, additional newborn testing is done to look for metabolic disorders or illnesses that may cause low blood sugar.

Treatment

Treatment of neonatal hypoglycemia depends on the presence of hypoglycemia symptoms, breast milk supply, and the ability to nurse or feed with a bottle and formula. Newborns with low blood sugar will need extra breast milk or formula feedings. 

Some newborns may need a sugar solution (glucose) intravenously through a vein, especially if the baby is unable to feed by mouth or if blood glucose is very low.

Treatment will continue for a few hours or days, or until the newborn maintains normal blood sugar levels. Premature babies, babies with infections, or those born at a low birth weight may need to be treated for a longer duration. If low blood sugar continues, the newborn will be given medication to increase blood sugar. 

In very rare cases, newborns can have a condition called congenital hyperinsulinism, which causes a low blood sugar that doesn't improve with standard treatment. Babies who have this condition may need part of the pancreas removed to reduce insulin production. 

A Word From Verywell

The outlook is good for babies born with low blood sugar, especially if they do not have symptoms or if they respond well to treatment. It is unlikely that neonatal hypoglycemia will affect babies as they grow, as long as they receive treatment quickly.

Very low levels of blood sugar that remain persistent may affect a newborn’s development.