Mouth breathing in infants is a common observation that often raises concern among parents. Understanding why babies typically breathe through their noses, when they might temporarily switch to oral breathing, and what signs point to a chronic problem is important for recognizing when to seek professional advice. This article explains the developmental context of infant respiration and the various causes behind mouth breathing.
The Developmental Baseline: Obligate Nasal Breathing
Newborns and young infants are considered preferential nasal breathers, strongly favoring breathing through their nose for the first few months of life. This preference is rooted in a unique combination of anatomical features, primarily the high position of the infant larynx compared to an older child or adult.
This high laryngeal position allows the soft palate and the epiglottis to almost touch, creating a functional seal. This configuration ensures that air passes through the nose directly into the lungs while the baby is simultaneously sucking and swallowing during feeding. This built-in mechanism allows for uninterrupted nourishment and respiration, which is necessary for survival in early infancy. The ability to reliably switch to mouth breathing only matures later, typically around three to six months of age.
Situational Causes: When Temporary Mouth Breathing Occurs
Temporary mouth breathing is normal once an infant develops the neurological ability to switch to oral breathing, usually sometime in the first half-year of life. The most common reason for this transient shift is acute nasal congestion, such as a mild cold or irritation from dry air, which partially or fully blocks the small nasal passages. When the nasal airway is obstructed, the baby instinctively opens their mouth to ensure sufficient airflow.
This temporary pattern is also observed during periods of intense vocalization, like a strenuous fit of crying or screaming, or briefly during active feeding if the nose is restricted by the breast or bottle. These situational episodes are generally not a cause for concern and resolve quickly once the congestion clears or the activity stops.
Underlying Conditions Leading to Persistent Mouth Breathing
When mouth breathing becomes a persistent pattern, even when the infant is well and their nose appears clear, it may signal an underlying physical obstruction in the upper airway. One common cause involves the lymphoid tissues in the throat, specifically enlarged adenoids or tonsils. If these tissues are swollen due to chronic inflammation or recurrent infection, they can partially block the nasal passage or the throat, forcing the baby to breathe through their mouth, especially during sleep.
Chronic allergic rhinitis is another frequent culprit, causing long-term inflammation and swelling of the nasal lining that constantly restricts airflow. Less common, but more serious, structural issues can also be responsible, such as a deviated septum, where the thin wall separating the nostrils is shifted, narrowing one or both nasal passages. In rare cases, a congenital condition called choanal atresia involves a bony or membranous blockage of the posterior nasal passage, which can be life-threatening in newborns who have not yet reliably mastered oral breathing.
Recognizing Signs That Require Medical Consultation
Parents should seek consultation with a healthcare provider if mouth breathing is constant or accompanied by other concerning symptoms. A consistent open mouth posture, snoring, or loud breathing during sleep indicates inadequate nasal airflow, which can affect sleep quality. The combination of a constantly dry mouth or chapped lips upon waking is a clear physical sign that the baby is not using their nose to breathe overnight.
Difficulty feeding is another indicator, as a baby who cannot breathe through their nose will often stop sucking to gasp for air. More urgent signs require immediate attention, including noticeable signs of respiratory distress, such as flaring nostrils, rapid or shallow breathing, or retractions (the skin pulling in around the ribs or neck with each breath). Prompt evaluation is necessary to identify and treat the root cause, preventing potential issues related to poor sleep, feeding, and development.