Orofacial development and neurophysiology of sucking during breastfeeding

Breastfeeding represents a complex neurophysiological process involving a sophisticated integration of sucking, swallowing, and breathing. It is a vital function that, beyond ensuring nutrition, profoundly influences the neuromotor, orofacial, and respiratory development of the newborn.
Understanding the mechanisms underlying sucking and respiratory coordination during feeding is essential to promote effective breastfeeding, prevent dysfunctions, and support harmonious growth.

Sucking is one of the newborn’s primary reflexes, already present in the fetal stage, and is mediated by a complex neural network located mainly in the brainstem. The key centers include:

• Nucleus of the solitary tract (NTS): receives sensory information from the oral cavity and pharynx.
• Nucleus ambiguus: controls the motility of the muscles involved in swallowing.
• Respiratory centers of the medulla: regulate breathing coordinated with sucking and swallowing.

Regulation of neonatal sucking, swallowing, and breathing

Sucking is characterized by the rhythmic alternation of phases of negative pressure (milk extraction phase) and release, which develop in a pattern coordinated with swallowing and breathing.
In term newborns, the sucking-swallowing-breathing (SSB) coordination usually follows a 1:1:1 ratio, where each suck is followed by a swallow and an inspiration.  This coordination represents a critical milestone in neuromotor development, which progressively improves with age and experience, ensuring effective and safe feeding.

Dysfunctions or delays in this process can negatively affect growth and neuromotor development. The posture adopted by the mother and the newborn during breastfeeding plays a crucial role in modulating neuromuscular coordination among sucking, breathing, and swallowing processes. Proper postural alignment favors optimal airway patency and orofacial structure alignment, reducing muscular effort and improving synchronization of the neurophysiological reflexes involved in neonatal feeding. This integrated coordination is essential to ensure efficient milk flow, the prevention of aspiration episodes, and hemodynamic stability of the newborn during feeding, thus contributing to better neurobehavioral and nutritional development.

Anatomical structures involved

The act of sucking involves:

• Oro-buccolingual muscles: genioglossus, mylohyoid, anterior digastric, orbicularis oris, buccinator.
• Soft palate and pharynx: essential for velopharyngeal closure during swallowing.
• Innervation:
  • Trigeminal nerve (V): control of the mandible and masticatory muscles.
  • Facial nerve (VII): mimetic muscles and lips.
  • Glossopharyngeal (IX), vagus (X), hypoglossal (XII): swallowing, lingual and pharyngeal motility.

Adequate maturation of these systems is a prerequisite for effective sucking, and any dysfunction at this level may result in feeding problems or later neuromotor disorders.

Nasal breathing: functional pillar for respiratory homeostasis

Breathing represents a critical and indispensable element during breastfeeding, as it ensures the continuity of oxygenation and the proper execution of sucking and swallowing processes. The airway must remain free and patent, with a functional preference for nasal breathing, which constitutes the ideal physiological model in newborns and infants.

Nasal breathing not only allows optimal airflow but also plays a protective role, filtering, humidifying, and warming inspired air, thus contributing to upper airway health.

During feeding, nasal breathing allows coordinated activity with sucking and swallowing, facilitating a rhythmic and synchronized sequence that minimizes the risk of aspiration and airway obstruction. Even partial nasal obstruction can interfere with this coordination, forcing the newborn to adopt less efficient oral breathing, which can lead to increased energy expenditure, feeding difficulties, and potential long-term issues such as craniofacial developmental alterations and chronic respiratory dysfunctions. Moreover, nasal breathing during breastfeeding contributes to maintaining correct tongue posture and supports the development of balanced orofacial musculature, fundamental elements for harmonious growth and for the prevention of oromotor and phonatory disorders.

Therefore, maintaining nasal airway patency through careful and early management of possible congestions or anatomical anomalies constitutes an essential aspect for the success and safety of breastfeeding.

Nasal breathing during feeding:

• Ensures adequate gas exchange without interfering with the feeding act.
• Promotes safe swallowing, preventing liquids from entering the airways.
• Stimulates proper craniofacial development through maintenance of physiological tongue and palate position.

Nasal obstruction, due to congestion, rhinopharyngitis, or anatomical malformations (e.g., short lingual frenulum or septal deviations), may alter SSB coordination. In these conditions, the newborn may compensate by adopting oral breathing, which reduces sucking efficiency and increases the risk of fatigue and intermittent hypoxia.

Early motor development: the formation of orofacial skills

Effective sucking requires the synergy of various anatomical and muscular structures:

• Tongue: must be mobile and capable of generating negative pressure to extract milk.
• Soft palate: closes the nasal airway during swallowing, preventing liquid reflux.
• Mandible: performs rhythmic opening and closing movements, coordinated with the tongue.
• Facial musculature: involved in stabilizing the areola and latching onto the nipple.
• Respiratory muscles: ensure rhythmic and synchronized airflow.

Breastfeeding plays a decisive role in the harmonious development of orofacial structures. Active and rhythmic sucking contributes to:

• Shaping the morphology of the palate and dental arches, reducing the risk of dental malocclusions.
• Strengthening facial and lingual musculature, essential for future masticatory, phonatory, and respiratory functions.
• Promoting physiological nasal breathing, fundamental for upper airway health and the prevention of chronic respiratory dysfunctions.
• Supporting correct postural development, through the functional connection between orofacial and cervical musculature.

Exclusive breastfeeding is associated with lower incidences of oral breathing, recurrent otitis, and myofunctional dysfunctions compared to artificial feeding. In the presence of breastfeeding difficulties, frequent regurgitations, irritability during sucking, or poor weight gain, a complete functional assessment of the newborn is essential, including:

• Assessment of the lingual frenulum (ankyloglossia)
• Observation of orofacial symmetry
• Postural analysis and global motricity
• Verification of S–S–B (suck–swallow–breathing) coordination

Early intervention by a multidisciplinary team (midwife, pediatrician, physiotherapist, osteopath, speech therapist) can prevent complications such as feeding difficulties, oral myofunctional disorders, and orthodontic problems.

Breastfeeding is a highly integrated activity, connecting vital, neuromotor, structural, and relational functions. Promoting, protecting, and supporting it from the very first hours of life not only ensures optimal nutritional intake but also fosters harmonious orofacial and neurological development, laying the foundations for long-term overall health.