Breathing is one of the first and most essential functions a newborn performs. But did you know that newborns primarily breathe through their noses?
If you’ve ever wondered, “When do babies start breathing through their mouth?”, you’re not alone.
This blog post breaks down everything you need to know—from how infant breathing works to when and why babies transition to mouth breathing.
We’ll also cover warning signs, causes, and when to see a doctor.
Why Do Newborns Breathe Through Their Nose?
At birth, babies are considered obligate nasal breathers. This means they instinctively breathe through their noses, not their mouths.
It’s a design feature of newborn anatomy that serves a few important purposes:
Allows babies to breathe while feeding
Helps filter, warm, and humidify the air
Supports a healthy sense of smell for bonding and feeding
This built-in mechanism keeps babies breathing efficiently even when they’re nursing or lying on their backs.
So, When Do Babies Start Breathing Through Their Mouth?
The ability to mouth-breathe typically develops between 3 to 6 months of age.
Before this, the soft palate and epiglottis are positioned in a way that makes mouth breathing inefficient and uncomfortable.
That said, in emergency situations—like if the nose is completely blocked—a baby can breathe through the mouth, even from birth.
However, because this doesn’t come naturally, some babies struggle with it, which is why nasal congestion in newborns can be serious.
Quick Tip: Always monitor your baby during colds. If they’re having trouble breathing and feeding, consult your pediatrician.
Is Mouth Breathing Normal for Babies?
Occasional mouth breathing can be normal, especially during:
Colds
Teething
Crying episodes
But persistent or regular mouth breathing is not typical and may signal a problem.
Signs Your Baby Is Breathing Through Their Mouth
Here are some telltale signs your baby may be breathing through their mouth:
Open mouth while sleeping
Dry mouth or lips
Difficulty feeding
Restless sleep or irritability
If these symptoms persist for more than a few days, it’s time to look deeper.
Common Causes of Mouth Breathing in Babies
There are several possible reasons why your little one might be breathing through their mouth:
1. Nasal Congestion
The most common reason. A stuffy nose from a cold, allergies, or dry air can force a baby to breathe through their mouth.
2. Enlarged Adenoids or Tonsils
These lymphatic tissues can block nasal airflow, especially if they’re enlarged.
3. Deviated Septum or Nasal Blockage
Structural abnormalities can cause chronic nasal obstruction.
4. Sleep Apnea
Though rare in infants, sleep apnea can cause interrupted breathing patterns and mouth breathing at night.
5. Habitual Behavior
Older infants might develop a habit of mouth breathing even after congestion has cleared.
How to Encourage Nasal Breathing
If your baby is mouth breathing due to congestion or habit, here are some helpful steps:
1. Use Saline Drops
A few drops in each nostril can loosen mucus and help clear the nasal passages.
2. Try a Nasal Aspirator
Use a bulb syringe or electric aspirator to gently remove mucus.
3. Use a Humidifier
Adding moisture to the air can prevent dryness and reduce irritation.
4. Elevate the Head Slightly
Slight elevation (under mattress, not with a pillow) can ease nasal breathing during sleep.
5. Keep the Air Clean
Avoid smoke, dust, or strong scents that may irritate your baby’s sensitive nasal passages.
When to Call the Pediatrician
Persistent mouth breathing should not be ignored. Contact your doctor if:
Mouth breathing lasts more than a few days
Your baby struggles to feed or gain weight
You notice snoring or gasping during sleep
There’s visible discomfort during breathing
Your baby seems lethargic or excessively irritable
Your pediatrician may refer you to a specialist such as an ENT (Ear, Nose & Throat doctor) to rule out structural issues or sleep disorders.
Can Mouth Breathing Affect Development?
Chronic mouth breathing isn’t just a breathing issue—it can also impact development:
Facial Structure: Can affect jaw growth and dental alignment
Speech: May contribute to delays in speech development
Sleep Quality: Poor sleep affects mood, behavior, and cognitive development
Early detection and intervention are key to preventing long-term problems.
Summary: Key Takeaways
| Question | Answer |
|---|---|
| When do babies start breathing through their mouth? | Around 3–6 months old |
| Can newborns breathe through their mouth? | Only in emergency situations |
| Is mouth breathing normal? | Occasionally yes, but not consistently |
| What causes mouth breathing? | Colds, congestion, adenoids, sleep apnea, or habit |
| When to see a doctor? | If it’s persistent, affects feeding, or disrupts sleep |
Final Thoughts
Babies are natural nose-breathers, and for good reason—it’s safer, healthier, and more efficient. While the ability to breathe through the mouth develops as they grow, persistent mouth breathing could signal something more serious.
Keep an eye on your baby’s breathing habits, especially during colds or if sleep becomes disrupted. When in doubt, don’t hesitate to reach out to your pediatrician.
