Scientific Article

The sucking instinct and suck training during infancy

Carina Kittelberger

The use of a pacifier is often a controversial topic and is regularly discussed within the profession, as well as between professionals and parents. The extent to which the pacifier affects the way in which a baby generally sucks, and the impact this has on the oral cavity, is addressed from a speech pathology perspective in this article.

The non-nutritive sucking reflex

Babies are born with a non-nutritive urge to suck. This sucking reflex is triggered as soon as the breast, a finger, or a pacifier touches the mouth. To feed, the infant must coordinate breathing, sucking, and swallowing. The cranial nerves, brain stem, and cortex interact to ensure that the newborn survives. So-called “non-nutritive” sucking calms and regulates the baby and is the precursor of nutritious sucking. Non-nutritive sucking improves digestion, behavioral organization, and pain management, as well as helping to prevent aspiration (1).

The use of pacifiers

If the baby is sucking to feed, this is called “nutritive sucking”. Sucking trains the muscles of the mouth, stimulates lower jaw growth, and ensures harmonious development of the upper and lower jaw. This interaction prepares the baby for biting, chewing, swallowing, and talking (2). Infants that are underweight at birth or are premature, often do not have the muscle strength essential for sucking. In situations like this, a (premature baby) pacifier can be used therapeutically, to help babies learn to coordinate sucking, swallowing, and breathing. Along with oral stimulation, this helps to steer children who are underweight at birth or premature away from the tube towards oral nutrition. Premature babies who were offered a pacifier could be steered more quickly from the tube to oral feeding, were breastfed significantly more, and could also be discharged sooner from intensive care (3). Studies also show that using pacifiers reduces the risk of sudden infant death syndrome, especially if they are used whenever the baby is placed for sleep (4,5). With breastfed infants, the pacifier should only be introduced once breastfeeding is well-established (4, 5).

If a pacifier is used beyond the natural urge to suck, this can have an effect on the jaw, teeth, facial muscles, and speech. Should bottle feeding, thumb sucking, or fingernail biting continue beyond the first year of life, this will also affect muscle balance in the oral cavity.

Speech Pathology Perspective

Physiologically, the rest position for the tongue is up against the palate. The thumb or a pacifier, especially one with a large and inflexible teat, makes it difficult for the tongue to assume this rest position in the mouth. The tongue being in the wrong position may result in an unphysiological pattern of swallowing, with the tongue pressing against the teeth instead of against the palate, as envisaged physiologically. So, from a speech pathology perspective, the choice of pacifier is an even more important consideration: the smaller, thinner, and more flexible the soother, the less space it needs in the oral cavity, and the easier it is for teeth to come through. Attention should also be paid to the material. The softer the teat, the easier it is for the tongue to press the soother against the palate (6). Various disorders can develop due to changes in the oral cavity. It is quite common for certain sounds to be interdental, that is, produced between the front teeth, instead of on the palate, and this can further move the teeth out of place (7). The space taken up by frequent and continuous thumb sucking and pacifier or bottle use may mean that teeth do not come through properly, which may produce a so-called “open bite”. An “open bite” has to be treated orthodontically, according to its severity (8).

Important Questions

With pacifier use, the following should be taken into account from a speech pathology perspective:

Indication: Is using the pacifier the right choice just now, or can I calm my baby some other way? By carrying them or gently cradling them, for instance?

Dosage: How long is the pacifier used in a certain situation? Does my child need a pacifier when playing in a sand pit?

Therapy duration: When should this be discontinued? It is a good idea to stop using the pacifier before the infant reaches 3 years of age.

Side effects: The possibility of undesirable effects should always be considered (9).

Carina Kittelberger

Speech pathologist

Carina Kittelberger qualified as a speech pathologist in 2009, at the University Hospital in Vienna. She made her way from Austria, to Germany, and finally, to the United States. She steadily increased her knowledge by working in ear, nose, and throat outpatient departments, neonatology, neurology, and in private practice. In 2013, she established the “Sprecherei”, the first logopedic practice in Vienna to specialize in children, and worked as a college lecturer for BAfEP, the training college for kindergarten teachers. She currently lives in California with her husband and two children.

References

1. Orovou, E. et al. Correlation between Pacifier Use in Preterm Neonates and Breastfeeding in Infancy: A Systematic Review. Children 9, 1585 (2022).

2. illi S, Tacha M. Kieferorthopädie kompakt. Alles über Diagnose, Behandlungsmethoden und Kosten. Welche Spange ist für wen geeignet? [Orthodontics compact. Everything about diagnosis, treatment methods, and costs. Which brace is suitable for who?] Vienna: Pub. Verein für Konsumenteninformation [Association for Consumer Information]. Vienna 2022, page 53.

3. Foster, J. P., Psaila, K. & Patterson, T. Non-nutritive sucking for increasing physiologic stability and nutrition in preterm infants. Cochrane Db Syst Rev 10, CD001071 (2016).

4. Hauck, F. R., Omojokun, O. O. & Siadaty, M. S. Do Pacifiers Reduce the Risk of Sudden Infant Death Syndrome? A Meta-analysis. Pediatrics 116, e716–e723 (2005).

5. Moon, R. Y., Carlin, R. F., Hand, I. & NEWBORN, T. T. F. O. S. I. D. S. A. T. C. O. F. A. Sleep-Related Infant Deaths: Updated 2022 Recommendations for Reducing Infant Deaths in the Sleep Environment. Pediatrics 150, (2022).

6. Furtenbach, M. Prävention orofazialer Dysfunktionen im Spannungsfeld von Kieferorthopädie und Logopädie – Anregung zur vermehrten Zusammenarbeit. Informationen Aus Orthod Kieferorthopädie 45, 209–219 (2013).

7. Fletcher, S. G., Casteel, R. L. & Bradley, D. P. Tongue-Thrust Swallow, Speech Articulation, and Age. J Speech Hear Disord 26, 201–208 (1961).

8. Schmid, K. M., Kugler, R., Nalabothu, P., Bosch, C. & Verna, C. The effect of pacifier sucking on orofacial structures: a systematic literature review. Prog Orthod 19, 8 (2018).

9. Furtenbach, M. Prävention orofazialer Dysfunktionen im Spannungsfeld von Kieferorthopädie und Logopädie – Anregung zur vermehrten Zusammenarbeit. Informationen Aus Orthod Kieferorthopädie 45, 209–219 (2013).