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Babies and Breathing – Why do babies prefer to breathe through their nose?

Sometimes it is easy to assume that babies are fully functioning “mini me’s”.  This was one of the first things medical school taught us never to assume.  Each age group has different needs and functioning capabilities.  Thus there are divisions of medicine into specialties like Pediatrics, Internal Medicine and Geriatrics.

It has been long understood that babies are obligate nose breathers.  Although this terminology defines breathing strictly through the nose, it is widely written to mean that babies “prefer” to breathe in air through their noses rather than their mouths. [1] (A corresponding article on Babies and Mouth-Breathing is also written for those interested.) All physiologically and anatomically normal babies have the capability to take in air through their mouth as it is most easily exhibited during crying.  Most babies can breathe through their mouths under situations where the nasal cavities are blocked due to congestion from colds, allergies or by other mechanical means.   However, this action is not easily achieved from newborns to babies 6~7 months old.

There is a study by Miller MJ et al. [2] which shows that the time it takes for the baby to breathe through their mouth from obstruction of the nasal passage decreases with older babies versus the newborn.   Another study by Rodenstein et al. [3] wanted to show that babies are not confined to nose breathing but able to breathe through their mouth.  However one baby was seen to take as long as 32 seconds before mouth breathing was initiated after manual nasal occlusion.  Try holding your breath for 30 seconds and you will feel how laboring and stressful it is to not breathe when you want to.  There is a case study in JAMA by Ulin et al.[4] which describes a 1 month old child being sent to the emergency room for severe respiratory distress and intermittant gasping for air due to nasal obstruction.  The struggle to breathe through the mouth can be attributed to the fact that the baby has yet to attain full maturity of muscle control in the mouth.

More importantly, there are differences in anatomic proportions of the baby versus the adult.  The oral airway of the infant is comparatively smaller than the airway of the adult.  The epiglottis of an infant nearly touches the soft palate.  Also, the infant’s tongue in ratio to the cavity of the mouth is larger than the adult and generally occupies most of the space in the infant’s mouth.  Through these anatomical observation, one can understand why babies prefer to breathe through their nose rather than their mouths.

As reiterated in the diagram, there is a smaller opening between the soft palate and the epiglottis.  This combined with less space in the mouth to take in air because of the tongue results in increased oral airway resistance.  Increases in oral airway resistance means that it takes more effort to breathe in the same amount of air.  Consider breathing air from a straw versus just breathing in air without one.  As the baby grows, the opening of the space between the soft palate and the epiglottis will increase and breathing through the mouth will be easier.

Hopefully this article clears up the question on why babies prefer to breathe with their nose.  Maybe it is after all correct to write that babies are obligate nose breathers.  The preference to breathe air is not due to whether babies “feel like” breathing air through the nose or mouth but rather limited to the nose for physiologic and anatomical reasons.

References:

  1. Miller MJ, Martin RJ, Carlo WA, Fouke JM, Strohl KP, Fanaroff AA.  J Pediatr. 1985 Sep;107(3):465-9. Oral breathing in newborn infants.
  2. Martin RJ, Miller MJ, Siner B, DiFiore JM, Carlo WA. J Appl Physiol. 1989 Jun;66(6):2522-6.  Effects of unilateral nasal occlusion on ventilation and pulmonary resistance in infants.
  3. Rodenstein DO, Kahn A, Blum D, Stănescu DC. Bull Eur Physiopathol Respir. 1987 May-Jun;23(3):223-6. Nasal occlusion during sleep in normal and near-miss for sudden death syndrome infants.
  4. Ulin LS, Bartlett GL Jr. JAMA. 1980 Apr 25;243(16):1657. Iatrogenic acute nasal obstruction in an obligate nose breather.

(This is the first in a number of articles which will feature the topic “Babies and Breathing“.)

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