The Sucking Reflex in Newborns

Do you know what’s involved in the sucking reflex? No doubt you’ve seen many times that when you bring something close to your baby’s mouth she reacts instinctively.
The Sucking Reflex in Newborns

Last update: 19 November, 2018

The sucking reflex in newborns is involuntary, and it may be a sign of abnormal development if it doesn’t work correctly. It’s a primitive instinct present in all mammals, and humans are no exception.

If you already are or about to be a nursing mother, find out all you need to know about the sucking reflex here.

What exactly is the sucking reflex?

Babies are born with the basic instincts they need for survival, and while they do depend on their parents caring for them, innate and involuntary abilities like the sucking reflex are essential for nursing to be possible.

Babies practice the sucking reflex from before birth, in the uterus. It can be perceived in ultrasound scans from around the fourth month of gestation.

It can be identified when the baby starts sucking his or her thumb. However, the amniotic fluid also plays an important role in the development of the sucking reflex, which goes hand in hand with the swallowing reflex.

The process shouldn’t be mistaken for a kind of classical conditioning; the sucking and swallowing reflexes are so ancient that they’re encoded in the genes of human babies, just as in the young of all mammals.

Practicing allows the baby to adjust the coordination so that the two reflexes compliment each other. At birth, the baby has to use the sucking reflex in combination with the swallowing reflex, thus allowing him to acquire the ability to correctly suck and ingest his mother’s milk.

The sucking reflex

The reflex is temporary

The mother’s breast isn’t required to determine the presence of the instinctive sucking reflex; putting a finger near the baby’s lips is enough for him to respond to the stimulus by wanting to suck.

The sucking reflex usually disappears when the baby is between six and nine months old. This doesn’t mean that this is the normal age to stop nursing, nor that the baby loses the ability to suck.

What happens is that at this stage, babies start to become aware of the execution of their movements. This means the sucking is now voluntary instead of reflexive, and that before the end of the first year of life, babies can demonstrate behaviors that represent rejection of the nipple or teat when they have no appetite.

Different types of sucking in babies

There are two ways to classify the suction reflex: one from the direct perspective of how the baby sucks, and the other concerned with the effect that the reflex has on the mother.

Both classifications consist of two subtypes: mature and immature sucking, and correct and incorrect sucking, respectively.

Below we’ll explain each:

Mature sucking

The sucking reflex in babies is defined as mature if the baby sucks between 10 and 30 times without stopping during nursing.

This indicates that the baby has no problem coordinating sucking, swallowing and breathing, and is able to effortlessly perform all three while breastfeeding.

Immature sucking

This is when the baby executes the reflex incorrectly or with difficulty. This can be inferred when the baby sucks between 3 and 5 times and then stops, either to rest or to breathe.

Immature sucking can be a sign of poor coordination between the impulses needed for nursing. When the baby seems to struggle to suck the mother’s milk and can’t manage to, there may be a problem such as a short lingual frenulum.

Correct sucking

Correct execution of the sucking reflex is fluid and natural, and in this sense it shouldn’t cause any damage or irritation to the mother’s breast.

This is generally the case with mature sucking. But while damage to the mother’s breast isn’t common with mature sucking, it can sometimes happen.

The sucking reflex

Incorrect sucking

This is when the baby hurts or damages the mother’s breast. It can result in painful breastfeeding or even the appearance of a nipple infection. If the infant struggles with sucking and is underweight, it can be a sign of a short lingual frenulum.

It’s important to note that this doesn’t necessarily imply a pathological issue. Immature or incorrect sucking can be due to early use of bottles or pacifierswhich can make it difficult for a baby to get used to the shape of the mother’s breast.

Other purposes of the sucking reflex

The sucking process doesn’t just allow the baby to feed without problems. It’s actually a two-way stimulus. The mother’s breast automatically stimulates the baby’s lips to begin to feed, and at the same time the baby’s sucking stimulates the mother to produce milk.

On top of this, the sucking reflex has a calming effect on the baby, more because the contact with the mother satisfies his need to feel safe rather than because of the feeding itself.

This is why it’s not unusual for babies to feel more comfortable sleeping at their mother’s breast, even when not feeding.