What are Common Causes of Low Blood Sugar in Newborns?

Low blood sugar in newborns is a condition in which the amount of sugar, or glucose, in the blood is lower than it should be. Approximately two of every 1,000 newborns develop low blood sugar. The mother's health, premature birth, congenital conditions, and stress during gestation and/or birth are all common causes of low blood sugar in newborns. Hypoglycemia, the medical term for low blood sugar, can be life threatening; close monitoring is essential for the health of at-risk babies.

Babies born to women with diabetes often develop low blood sugar. During gestation, a baby's body becomes accustomed to producing extra insulin in response to the mother's high sugar levels. At birth, the baby's body — which is still producing extra insulin — uses up all of the sugar stored in the liver. When this happens, low blood sugar develops.

Premature infants and infants small for gestational age may also experience low blood sugar. This is especially true for babies with low birth weight. These babies either cannot store enough sugar in their livers or their livers are too immature to function well outside the womb. When their stores of glucose are exhausted, blood sugar levels may drop.

Congenital conditions such as hypopituitarism, hyperinsulinism, and glycogen storage diseases may be a cause of low blood sugar in newborns. In hypopituitarism, the pituitary gland does not tell the other glands to secrete the correct amount of hormones. In hyperinsulinism, too much insulin is secreted into the blood stream and stores of sugar in the liver are used up too quickly. Glycogen storage disease consists of 14 different disorders that impact the ability of the liver to store carbohydrates as glycogen.

Stress during gestation or birth may cause low blood sugar in newborns. If the mother has poor eating habits during pregnancy, fasts, or produces inadequate breast milk, her baby may be more likely to develop low blood sugar. Birth asphyxia, i.e., when the baby receives insufficient oxygen during pregnancy or during birth, may also cause low blood sugar in newborns. Babies who are not fed regularly, or who eat sparingly, may also show signs of low blood sugar.

Low blood sugar in newborns can be very dangerous. In situations where blood sugar remains low for a long period of time, seizures or brain injury may develop. Babies with low blood sugar may not show any obvious symptoms. Those who do show symptoms of hypoglycemia may become jittery, lethargic, have low tone, or a low body temperature. They may also become cyanotic, or blue, and may even stop breathing. Caretakers of babies at risk for hypoglycemia need to be aware of the signs and symptoms so that they can respond quickly if the condition develops.