Low Blood Sugar in Newborns: Why Does It Happen?

What is Hypoglycemia? 

Hypoglycemia is the term used to describe low blood sugar. It’s an important part of your newborn’s care after he or she is born. Everyone needs glucose to function. Adults typically have blood sugars between 4 mmol/L and 8 mmol/L and are able to maintain these levels because of a hormone called insulin.

When we eat a meal, carbohydrates break down and turn into usable energy for our body. In response to this, our pancreas will produce insulin and regulate how much sugar is circulating in our blood.


When your baby is cozy in your womb, you are giving them everything they need- food, energy, and your insulin. If your blood sugar is normal, so is theirs. When baby is born and we cut their umbilical cord their body tells them to start regulating sugar on their own. But for some babies, this can be hard to do on their own. This is why your nurse or midwife will be closely watching for signs of hypoglycemia.

Any baby can have low blood sugar. However, there are a few groups that are more at risk than others.

Babies born before 37 weeks gestation are at high risk for hypoglycemia because their body isn’t fully ready to start managing insulin production on their own. They may also find feeding more difficult because their suck-swallow-breathe coordination needed for effective feeds is immature.



Babies who are term but are small for gestational age (less than 10th percentile) and babies who are large for gestational age (greater than 90th%) will also be at risk for having low blood sugar. A small baby will have higher carbohydrate needs than a baby who is larger. Adversely, so does a large baby because they have so much more weight to manage at birth.

If mama has insulin dependent diabetes or gestational diabetes, or if your babe had a traumatic birth and required assistance with breathing, they will be monitored for low blood sugar as they can have difficulty adjusting to living outside of the womb.


What does this look like in the hospital?

It’s important for baby to have an “effective feed” within 60 minutes of birth. Whether baby is breastfeeding or formula feeding, this needs to be a priority. Immediately after birth, baby will be placed on your chest and you will have an opportunity for skin-to-skin time. This helps stimulate milk production for mama. If baby is unwell, you may not be able to do skin-to-skin right away. As soon as it is safe to do so the nurse will bring baby to you.

Newborns don’t need very much colostrum to have an effective feed. You want to watch for sucks and swallows, and ensure that baby is comfortable and relaxed with feeding. Your health care providers will help you with breastfeeding and ensuring baby has a good latch.



If baby is at risk for hypoglycemia, they will check his blood sugar before a feed by poking his foot with a very small needle and collecting a drop of blood. Your nurse will record the level and then check again an hour after his feed. If your baby is at risk for low blood sugar, your nurse will ask you to try to feed every 3 hours. Even if baby is sleeping. If baby has had two good blood sugars (over 2.6 mmol/L) before two feeds, they can check the levels less often. You may hear your baby cry when they poke his foot. It’s very hard to listen to as a mama. Have your babe’s arms swaddled and allow them to suck on a soother while this happens to reduce their stress. It is important that baby is warm when they check the level, so keep baby bundled until right before the nurse pokes him.

This can be a lot of information to think about right after you have a baby. Prenatal education can reduce stress. If you know what to expect, you will feel like you have more control of a situation. Advocate for yourself and your baby so you are able to stay informed during this process.

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