During pregnancy, a baby’s energy needs are supported mainly by transfer of sugar (glucose) via the placenta.

Once a baby is born and the umbilical cord has stopped pulsating, the maternal sugar supply is removed.

In the first few hours after birth, a baby’s blood sugar levels will begin to naturally fall but tend to spontaneously begin to rise in the 24 hours after birth.

Low Blood Sugar After Birth – 5 Important Facts

This transient low blood sugar after birth is a normal process and applies to all babies, regardless of whether they are breastfed, formula-fed, or mixed-fed.

They all tend to follow the same pattern of blood sugar levels, with an initial fall over the first two hours of life followed by a gradual increase over the next 96 hours.

Even if healthy, full-term babies are not fed, this transient low blood sugar is usually self-limited without clinical signs.

Here are five important facts about low blood sugar after birth.

#1: Babies Can Use Alternate Energy Sources

A baby’s body has many in-built ways of being able produce alternative energy sources to compensate well for the normal and transient low blood sugar after birth.

One way babies do this is by producing and using ketone bodies as an alternative energy source. A baby’s brain has an enhanced ability to use ketone bodies as energy.

Interestingly, formula-fed babies tend to have increased blood sugar levels and lower levels of ketone bodies than breastfed babies. This suggests formula-fed babies may be less able to use ketone bodies as an alternative energy source.

#2: Routine Testing Isn’t Necessary And Potentially Harmful

Since low blood sugar is a normal part of babies adapting to life outside the uterus, routine testing of healthy, full-term babies after birth is not necessary.

It’s also potentially harmful as it can result in babies being supplemented unnecessarily with formula in the early days after birth. Unnecessary supplementation with formula can interrupt the establishment of breastfeeding and reduce a mother’s confidence in her breastfeeding ability.

You can read more about this in Formula Supplementation After The Birth – Will Your Baby Need It?

#3: Some Babies Need To Be Monitored

There are some babies who are at increased risk for developing significant low blood sugar levels and will need to have their blood sugar levels routinely monitored.

Such babies are born with insufficient fuel stores and include those who are born prematurely, small for gestational age or have low birth weight.

Babies born to women with diabetes (especially if it’s poorly controlled) may make too much insulin resulting in lower blood sugar levels.

For a complete list of risk factors see Table 3 in the Academy of Breastfeeding Medicine’s Hypoglycemia protocol.

#4: Skin-To-Skin Contact Has Benefits

Skin-to-skin contact following birth has many benefits, including babies maintaining higher blood sugar levels.

This happens because uninterrupted skin to skin helps a baby keep warm, which means not having to use up energy to try and keep their temperature stable. Mothers are better able to pick up their babies feeding cues and feed on demand, helping to maintain higher blood sugar levels.

For this reason, even if an ‘at-risk’ baby needs closer monitoring for low blood sugar, skin-to-skin contact with his mother would still be the ideal place for him to be.

Early (within the first hour after being born) and frequent (10-12 times every 24 hours at least in the first few days) breastfeeding also help meet the nutritional and metabolic needs of healthy full-term babies.

#5: Management For Very Low Blood Sugar Varies

The management for very low blood sugar levels varies. For example, it can depend on whether the baby has clinical signs of low blood sugar or not. Some common clinical signs of low blood sugar include:

Irritability, tremors, jitteriness
High-pitched cry
Lethargy
Poor suck or refusal to feed
Rapid breathing
Trouble maintaining temperature.

According to the Academy of Breastfeeding Medicine’s Hypoglycemia protocol, low blood sugar levels requiring treatment must be confirmed by laboratory level results, especially in babies with no clinical signs.

If confirmed, babies with no clinical signs should:

Continue frequent breastfeeding (every 1-2 hours) or be fed 1-5mL/kg of expressed breastmilk (a mother’s own breastmilk or donor breastmilk if available and a mother makes an informed decision to use it) or formula (if breastmilk is not available or not available in sufficient quantities). Some mothers with babies at risk of clinically significant low blood sugar levels express colostrum antenatally to have it available after the birth to avoid formula in case their baby need treatment for low blood sugar levels after birth.
Have blood sugar levels rechecked before subsequent feeds until the measure is acceptable and has stabilised.
If low blood sugar levels remain, begin intravenous glucose therapy and breastfeeding to be continued during this.

If confirmed, babies with clinical signs of low blood sugar (or blood sugar levels less than 1.1-1.4mmol/L) should:

Begin intravenous glucose therapy. Blood sugar levels should be maintained greater than 2.5mmol/L.
Continue frequent breastfeeding.
Have blood sugar levels rechecked before feeds while gradually weaning from the intravenous glucose, until values are stabilised off it.

Healthy, full- term babies are well equipped to transition from the continual supply of nutrients via the placenta to life outside the uterus without the need for routine testing or interruption to the normal breastfeeding process. Only babies who are ‘at-risk’ should have their blood sugar levels monitored and treated as medically indicated.