Sucking Reflex in Newborns: What You Need to Know

If you have a baby, you surely know about the sucking reflex. We'll explain everything you need to know about this primitive sense, which all human beings have.

The sucking reflex in newborns is one of the most important skills for the beginning of life, as it allows the baby to feed from the mother’s breast or bottle. It’s part of innate reflexes that are physiological responses for a baby’s psychomotor development.

Up to six months of age, infants should be fed only breast milk or formula. This is because infants under six months of age can’t hold their heads up or sit in a high chair, which would cause a risk of choking.

In addition, before six months of age, infants still have an active sucking reflex, which is the expulsion of non-liquid food with the tongue to the outside.

Newborns need this sucking reflex to ensure proper feeding with liquids and to acquire the benefits of breast milk. We’ll now tell you everything you need to know about this reflex in babies.

What is the sucking reflex in newborns?

It’s an instinctive reflex that occurs seconds after birth to ensure survival. Sucking requires an integration of sensory and motor activities to ensure a sufficient intake of food with correct assimilation.

In fact, Inostroza assures that this reflex begins while the baby is still in the womb. It begins at 17 weeks and matures throughout development until week 37, when it’s fully matured.

The sucking cycle

The sucking cycle consists of expressing milk with the baby’s lips outward. These, together with the cheeks, form a seal that prevents leakage.

Then comes the swallowing. With each sucking there’s a swallowing action, which is a fundamental step that must be coordinated. Breathing throughout this process is continuous, although it’s interrupted for half a second to help the bolus enter the pharynx.

Types of suction in newborns

Inostroza says that there are three types of sucking depending on the degrees of maturity. Immature sucking is 3 to 5 sucks, then the baby breathes because they aren’t able to suck and breathe at the same time. There’s no coordination.

Intermediate ranges from 6 to 10 sucks followed by apneas, in which there’s no complete coordination of the sucking cycle. Mature sucking ranges from 10 to 30 suctions with small rest intervals, but there’s good coordination between sucking, swallowing, and breathing.

There’s also nutritive and non-nutritive sucking. The nutritive one is activated when the mouth comes into contact with the breast or bottle and is for feeding. Non-nutritive sucking is when it’s activated on coming into contact with something else.

How to stimulate the sucking reflex

You can stimulate the sucking reflex by placing the mother’s breast inside the baby’s mouth, although orofacial exercises can also be practiced. The latter is often for children with oral dysfunctions that don’t allow them to exercise the correct sucking process.

These exercises consist of massaging the baby’s palate on the gum over the tongue and with the extension and retraction movements of the finger. It must be a clean finger and you must avoid reaching the bottom of the tongue to avoid the gag reflex.

What happens if there’s no sucking reflex in the newborn?

When babies don’t have this reflex, it means that they have a developmental abnormality. Most often it’s a neurological alteration at the level of the spinal cord. In these cases, the mother should seek professional help. If the baby isn’t fed as it should be, developmental disturbances may occur.

Premature babies or those with physical abnormalities often suffer from a lack of this reflex. However, most of the disorders are usually at the level of the jaw and tongue.

Disorders where the tongue is attached to the floor of the mouth can minimize this reflex; this condition is sublingual frenulum. In addition, other problems such as cleft palate, the tongue being too large to rest in the mouth, and delayed lower jaw all make sucking difficult.

How is the sucking reflex related to milk production?

The sucking reflex sends a signal to the mother’s brain to produce the hormone prolactin and, in turn, breast milk. This is what continues to produce milk after the first time a mother breastfeeds her child. However, it’s also important for the baby to empty the breast; the body will then seek to fill it and continue producing.

Milk is produced in the mammary glands of each breast. These glands have alveoli, empty spaces that fill with milk, and the walls of these alveoli contain lactocytes, cells capable of producing and synthesizing milk.

In response to the baby’s sucking, the nerves stimulate the lactocytes to produce milk. Sucking squeezes the alveoli containing the breast milk, which passes into the ducts and flows into the nipple to nourish the baby.

The baby won’t only suckle out of hunger, but also to feel protected and reassured. That’s why, when they cry and you offer them a pacifier, finger, or breast and they take it, they stop crying. You can also see newborns doing the sucking gesture while they sleep.

The sucking reflex, a natural reflex

This reflex is a vital natural act for the beginning of their lives; it will make them feel nourished and full of peace. If you notice that your child is having difficulty sucking, see a lactation specialist.

Immature sucking doesn’t have to mean the end of breastfeeding. With time, effort, and professional help, you’ll be able to breastfeed your baby.