Are Infants Really Obligate Nasal Breathers?

You’re on your third night shift of the week, and it’s just gone 03:00. A two-day-old term neonate is brought into the emergency department by two understandably frazzled parents. “She just won’t settle,” they say. “She’s snuffly and breathing really fast.” The baby is mildly tachypnoeic with nasal congestion and a few soft grunts. You glance at the oxygen saturations (96% in air) and then, instinctively, say what you’ve been taught a hundred times before:

“Don’t worry — newborns are obligate nasal breathers. She probably just needs her nose cleared out.”

But then something tugs at you — a quiet voice of doubt. Wait… are they really? You were told they can’t breathe through their mouths. But where did that idea come from? And how sure are we about it?

Ask most paediatricians — or even most medical students — and they’ll likely tell you that neonates are obligate nasal breathers. It’s a fact that gets handed down in lectures, whispered on postnatal wards, and dropped into textbook chapters with the same confidence as “babies have more bones than adults.”*

“They can’t breathe through their mouths.”
“It’s why nasal congestion is such a big deal.”
“It’s just how they’re built.”

The concept is so widely accepted that it’s rarely questioned. It gets taught early and often, sometimes without nuance, almost always without reference.

But here’s the thing:

“Turns out the idea that babies can’t breathe through their mouths is based more on anatomy textbooks than actual physiology.”

The “obligate nasal breather” label doesn’t come from rigorous physiological trials or large-scale observational studies. It comes from anatomical inference — the assumption that the shape of the neonatal airway must mean what we think it means.

So… have we ever actually tested it?

Where Did This Idea Come From?

So, where did the idea come from — that neonates can only breathe through their noses?

The earliest formal reference we could trace is a short article by Moss in 1965, titled The veloepiglottic sphincter and obligate nose breathing in the neonate. In it, Moss proposed that the anatomical configuration of a newborn’s upper airway — particularly the close proximity of the soft palate and the epiglottis — forms a kind of valve or seal. This, he suggested, creates a structural barrier between the oropharynx and the larynx, effectively forcing airflow through the nose.

It was a compelling idea. And while Moss didn’t perform any experimental work to test this theory, his anatomical observations made their way into textbooks and teaching slides — and from there, into generations of paediatric practice. The phrase “obligate nasal breather” was born.

But the transition from anatomical theory to clinical truth happened quietly and without much scrutiny. For decades, it was accepted on face value.

Interestingly, even long before Moss, people seemed to understand that a baby with a blocked nose wasn’t a baby who was doing well. In fact, a 15th-century English manuscript describes a folk remedy for nasal congestion involving the boiling of stale ale, mustard seed, and ground nutmeg — with the vapours inhaled under a cloth to clear the airways. No pulse oximeters. No nasal aspirators. Just a monk with some questionable ingredients and a very snuffly baby.

So, even in medieval times, the idea that infants needed clear nasal passages to breathe and feed was felt, if not scientifically proven. But the leap from nasal preference to nasal necessity? That’s something we really only started claiming in the last 60 years.

What Does the Evidence Say?

So, someone finally asked the question: Can we actually test this?

Yes — and they did. Starting in the early 1970s, a handful of researchers designed studies that set out to answer this question directly. They took neonates — some just hours or days old — and gently but deliberately blocked both nostrils, usually while the babies were asleep. The aim? To see if, and how quickly, the infants would start breathing through their mouths instead.

This wasn’t a simulation or theoretical exercise. These were real-time physiological tests, done under close monitoring, usually with airflow sensors or video imaging, and always for a defined period — 15, 25, sometimes 30 seconds — before intervention.

In one of the largest studies, conducted by Swift and Emery in 1973, researchers applied nasal occlusion to 100 neonates and 59 older infants and timed how long it took them to switch to mouth breathing. Most of the babies did so within 25 seconds, but a small number did not.

In another study, Rodenstein and colleagues used real-time X-ray imaging to observe infants as their nasal passages were blocked. They watched for jaw movements, oral airflow, and signs of respiratory compensation. All infants in that group eventually switched to mouth breathing, but the time it took varied widely, with some taking over 30 seconds to respond.

What these studies found was consistent:

• Neonates can mouth breathe if their noses are blocked.
• But the transition isn’t always immediate, and in some cases, it doesn’t happen at all within the tested time frames.
• Sleep state, developmental maturity, and individual variation influence the response.

This has important clinical implications. Thirty seconds of ineffective breathing — in a preterm baby or a neonate with bronchiolitis — can be a long time.

We’ll summarise the six key studies next, but the bottom line is this:
The data do not support the idea that neonates must breathe through their noses. But the idea that they strongly prefer to do so — and may struggle to switch quickly — absolutely is.

Summary of Key Studies

Anatomy and Physiology: Why the Myth Feels True

Let’s be honest — the idea that neonates are obligate nasal breathers feels right.

When you look at their tiny, squishy faces, their mouths often sit open but inactive, especially during sleep. Add in the chaos of feeding, the snuffling of a bronchiolitic baby, and the panic that sets in when the nose is blocked — it’s easy to see how this belief took hold. And the anatomy… doesn’t help.

What makes nasal breathing easier in neonates?

The “veloepiglottic seal” and high laryngeal position

In neonates, the larynx sits higher in the neck than in older children or adults. This elevated position brings the epiglottis into close contact with the soft palate, creating what has been termed a veloepiglottic seal. It’s not a true anatomical seal, but rather a close apposition that functionally separates the nasal and oral passages.

This configuration forms a nearly continuous airway from the nares to the trachea, making nasal airflow highly efficient and ideal for breathing during feeding. However, it also makes oral breathing more difficult, particularly when airway tone is low (like during sleep).

Tongue size and oral cavity proportions

The tongue is relatively large and fills most of the oral cavity, particularly when the baby is just lying there. This further limits the space available for oral airflow and contributes to airway resistance when nasal breathing is compromised.

Narrow oropharynx and posterior tongue position

The back of the tongue lies close to the posterior pharyngeal wall. During quiet sleep, especially in REM, the pharyngeal muscles are atonic — meaning the airway can easily collapse or become obstructed unless the nose is clear.

These features work together to promote nasal breathing as the path of least resistance.

Importantly, this isn’t a permanent setup. As infants grow:

• The larynx descends
• The oral cavity enlarges
• The soft palate-epiglottis distance increases
• Mixed nasal and oral breathing becomes more common and efficient

This transition typically occurs between 4 and 6 months of age, and a more adult-like airway pattern is established by around one year.

So while neonates aren’t truly “obligate” nasal breathers, they are anatomically biased towards it, especially in the first few weeks of life. They are preferential nasal breathers.

Clinical Implications

So if neonates can technically mouth-breathe, but don’t do it efficiently or quickly, what does that mean for the real world?

Quite a lot.

Upper respiratory infections and nasal congestion

It’s bronchiolitis season. A newborn comes in, feeding poorly and “a bit snuffly,” but still maintaining oxygen saturations in air. If you’ve been taught they must breathe through their nose, you might overreact. If you think they’ll easily switch to mouth breathing, you might underplay it.

The truth? A congested nose can be a serious problem, not because they can’t mouth-breathe, but because they might not do it quickly enough. Especially during sleep. Especially when already compromised.

Choanal atresia and bilateral nasal obstruction

One of the classic presentations of bilateral choanal atresia is cyclical cyanosis that improves with crying. Why? Because crying forces the mouth open, allowing airflow when the nose is completely blocked.

Recognising that not all neonates will mouth-breathe effectively when obstructed is key to making the diagnosis and acting early.

Feeding difficulties

Nasal patency matters for feeding. When the nose is congested or structurally narrowed, neonates struggle to coordinate suck-swallow-breathe cycles. This can lead to desaturations, poor intake, and maternal distress, and often presents subtly.

The lesson here: always check the nose in any neonate with feeding issues.

Intubation, airway management, and ENT planning

For anaesthetists and ENT surgeons, knowing that neonates prefer nasal breathing changes how we think about:

• Preoperative planning (e.g. for nasal masses or stenosis)
• Post-extubation monitoring
• Surgical interventions that may temporarily occlude the nasal airway

Understanding that mouth breathing is possible but not reliable reinforces the need for cautious airway strategies.

Neonates aren’t obligate nasal breathers. But in certain situations, they can behave as if they are — and that’s where risk lies.

So… Are They?

After all that — the history, the anatomy, the physiology, the studies, and the practical realities — it’s time to answer the question we started with:

Are neonates obligate nasal breathers?

No.
But also — not quite not, either.

Here’s what we know:

They overwhelmingly prefer nasal breathing. Their airway anatomy is geared for it, especially during feeding and sleep.

They can mouth-breathe — but that transition may be slow, inconsistent, and unreliable, particularly in the early weeks and during REM sleep.

In a well baby, a blocked nose might just be a nuisance.

In a sick, preterm, or sleeping baby, it might be a problem.

That’s why the distinction matters. “Obligate” suggests impossibility. “Preferential” suggests bias with capacity — and that’s much closer to the truth.

The best summary?

Neonates are preferential nasal breathers. Not obligate. But in certain conditions, they can behave as if they are — and that’s where clinical awareness counts.

This isn’t a minor correction in terminology. It’s a subtle but important reframing — one that can influence how we assess risk, manage airways, interpret symptoms, and avoid assumptions.

And like so many things in medicine, it’s a reminder that black-and-white statements rarely do justice to the physiology.

Keep Asking Questions

This post started with a question — not from a textbook or a lecturer, but from someone who stopped to wonder whether what he’d been taught actually held up.

We don’t write this post to be pedantic or provocative. We write it because getting these details right can change how we manage a struggling baby at 3am. It can change how we explain things to worried parents. It can change how we teach the next generation of paediatricians.

So to every reader who paused during a ward round and thought, “Is that actually true?” — keep doing that.

“Be sceptical of everything you read…” – Ken Milne

Yes, even this post. Read the primary studies. Question the assumptions. Follow the footnotes. Dig a little deeper.

That’s what makes you the kind of clinician we’d want looking after our children.

*Do babies have more bones than adults?

Babies really do have more bones than adults: around 270 at birth, compared to 206 in adulthood. As they grow, many of these bones fuse — particularly in the skull, spine, and pelvis.

So, while “obligate nasal breathing” may not be as clear-cut as we once thought, it’s a good reminder that some textbook facts stand up, while others deserve a second look. Knowing the difference? That’s where the magic of clinical curiosity lives.

References

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Coppens T, Rosant O, Dégrugilliers L, Rames C, Liistro G, Reychler G, Bayat S. Development of the nasal cavity during infancy: A restrospective CT imaging study. European Respiratory Journal. 2014 Sep 1;44(Suppl 58).

Cozzi F, Morini F, Tozzi C, Bonci E, Cozzi DA. Effect of pacifier use on oral breathing in healthy newborn infants. Pediatr Pulmonol. 2002;33(5):368–373.

deAlmeida VL, Alvaro RA, Haider Z, Rehan V, Nowaczyk B, Cates D, et al. The effect of nasal occlusion on the initiation of oral breathing in preterm infants. Pediatr Pulmonol. 1994;18(6):374–378.

Martin RJ, Miller MJ, Siner B, DiFiore JM, Carlo WA. Effects of unilateral nasal occlusion on ventilation and pulmonary resistance in infants. J Appl Physiol. 1989;66(6):2522–2526.

Miller MJ, Martin RJ, Carlo WA, Fanaroff AA. All neonates are not obligate nose breathers. Pediatr Res. 1984;18:336A.

Miller MJ, Martin RJ, Carlo WA, Fouke JM, Strohl KP, Fanaroff AA. Oral breathing in newborn infants. J Pediatr. 1985;107(3):465–469.

Moss ML. The veloepiglottic sphincter and obligate nose breathing in the neonate. J Pediatr. 1965;67(2):330–331.

Polgar G, Kong GP. The nasal resistance of newborn infants. J Pediatr. 1965;67(4):557–567.

Rodenstein DO, Perlmutter N, Stănescu DC. Infants are not obligatory nasal breathers. Am Rev Respir Dis. 1985;131(3):343–347.

Rodenstein DO, Kahn A, Blum D, Stănescu DC. Nasal occlusion during sleep in normal and near-miss for sudden death syndrome infants. Bull Eur Physiopathol Respir. 1987;23(3):223–226.

Shatz A, Arensburg B, Hiss J, Ostfeld E. Cervical posture and nasal breathing in infancy. Cells Tissues Organs. 1994;149(2):141–145.

Swift PGF, Emery JL. Clinical observations on response to nasal occlusion in infancy. Arch Dis Child. 1973;48(12):947–951.