Medical Conditions

Subglottic Stenosis (Narrowed Airway Below Vocal Cords)

Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist

Content reviewed against published AAP, NIH, AAO-HNS guidelines

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If your baby has been diagnosed with or you suspect subglottic stenosis (narrowed airway below vocal cords), here is what the evidence says.

The short answer

Subglottic stenosis is a narrowing of the airway just below the vocal cords. It can be congenital (present from birth) or acquired, most commonly following prolonged intubation in premature or critically ill newborns. Symptoms include biphasic stridor (noisy breathing on both inspiration and expiration), recurrent or severe croup episodes, and exercise intolerance. Mild cases may be monitored as the child grows and the airway widens, while moderate to severe cases may require surgical intervention such as endoscopic dilation or open airway reconstruction.

Key takeaways

  • Subglottic stenosis is a narrowing of the airway just below the vocal cords. It can be congenital (present from birth) or acquired, most commonly following prolonged intubation in premature or critically ill newborns. Symptoms include biphasic stridor (noisy breathing on both inspiration and expiration), recurrent or severe croup episodes, and exercise intolerance. Mild cases may be monitored as the child grows and the airway widens, while moderate to severe cases may require surgical intervention such as endoscopic dilation or open airway reconstruction.
  • Usually normal when: Your child had mild croup once and recovered fully without complications
  • Call your doctor if: Your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care
  • Varies by age — see the age-by-age breakdown below
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What Parents Should Know

According to AAP, NIH, AAO-HNS guidelines, subglottic stenosis is a narrowing of the airway just below the vocal cords. It can be congenital (present from birth) or acquired, most commonly following prolonged intubation in premature or critically ill newborns. Symptoms include biphasic stridor (noisy breathing on both inspiration and expiration), recurrent or severe croup episodes, and exercise intolerance. Mild cases may be monitored as the child grows and the airway widens, while moderate to severe cases may require surgical intervention such as endoscopic dilation or open airway reconstruction. At 0-3 months, congenital subglottic stenosis may present with stridor from birth, while acquired stenosis typically develops days to weeks after extubation in a baby who was intubated in the NICU. The stridor is often biphasic, meaning it is heard during both breathing in and breathing out, which distinguishes it from laryngomalacia. If your baby was intubated and develops new-onset stridor, breathing difficulty, or feeding issues after extubation, your medical team will likely evaluate for subglottic stenosis with endoscopy. It is generally considered normal when your child had mild croup once and recovered fully without complications. However, you should contact your pediatrician promptly if your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
Your child had mild croup once and recovered fully without complications
Your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care
A baby who was intubated briefly has no stridor or breathing difficulty after extubation
Your child turns blue, becomes extremely agitated, or is unable to speak or cry during a breathing episode -- call 911
Your child with known mild stenosis is growing well, feeding normally, and the stridor is stable or improving
Your child has had croup 3 or more times in a year, or croup episodes are unusually severe
Recurrent croup episodes are becoming less frequent and less severe as your child gets older
Your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty

By Age

What to expect by age

0-3 months

Congenital subglottic stenosis may present with stridor from birth, while acquired stenosis typically develops days to weeks after extubation in a baby who was intubated in the NICU. The stridor is often biphasic, meaning it is heard during both breathing in and breathing out, which distinguishes it from laryngomalacia. If your baby was intubated and develops new-onset stridor, breathing difficulty, or feeding issues after extubation, your medical team will likely evaluate for subglottic stenosis with endoscopy.

3-12 months

Mild congenital subglottic stenosis may become more apparent as your baby grows more active and breathes harder. A hallmark sign is recurrent croup, occurring more frequently than expected or being unusually severe. If your baby is diagnosed with croup more than 2-3 times in one season, or if croup requires hospitalization, your pediatrician may refer to a pediatric ENT to evaluate for underlying airway narrowing. Mild stenosis is often managed expectantly, as the airway grows and the relative narrowing improves.

1-3 years

Mild subglottic stenosis often improves significantly by age 3-4 as the airway grows in diameter. Recurrent croup episodes should become less frequent and less severe over time. For moderate stenosis, endoscopic procedures such as balloon dilation or laser treatment may be used to widen the airway. Severe stenosis (Grade 3 or 4) may require laryngotracheal reconstruction, a major surgery that uses a cartilage graft to expand the airway. The success rate for these procedures is high at experienced pediatric airway centers.

3+ years

Most children with mild to moderate subglottic stenosis outgrow their symptoms as the airway grows. Children who underwent surgical reconstruction typically do well, though long-term follow-up with an ENT specialist is important to monitor for restenosis. Some children may have a barky voice or mild exercise intolerance. After successful treatment, most children lead fully active lives without significant airway limitations.

What to Tell Your Pediatrician

  • Describe when you first noticed subglottic stenosis (narrowed airway below vocal cords) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your child has had croup 3 or more times in a year, or croup episodes are unusually severe.
  • Mention if your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • Your child had mild croup once and recovered fully without complications
  • A baby who was intubated briefly has no stridor or breathing difficulty after extubation
  • Your child with known mild stenosis is growing well, feeding normally, and the stridor is stable or improving
  • Recurrent croup episodes are becoming less frequent and less severe as your child gets older
Mention at your next visit when...
  • Your child has had croup 3 or more times in a year, or croup episodes are unusually severe
  • Your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty
  • Your child has noisy breathing that is present both when breathing in and breathing out
Act now when...
  • Your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care
  • Your child turns blue, becomes extremely agitated, or is unable to speak or cry during a breathing episode -- call 911

What You Can Do at Home

  • Keep track of when you notice subglottic stenosis (narrowed airway below vocal cords) — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that your child had mild croup once and recovered fully without complications — this is generally within the range of normal.
  • At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
  • While monitoring at home, seek immediate care if your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care.

Laryngomalacia (Floppy Airway)

Laryngomalacia is the most common cause of noisy breathing (stridor) in infants. It occurs when the tissue above the vocal cords is unusually soft and floppy, causing it to collapse inward during breathing and create a high-pitched squeaky sound. It typically appears within the first 2 weeks of life, peaks in severity at 4-8 months, and resolves on its own by 12-18 months. Most cases are mild and require no treatment beyond monitoring.

Tracheomalacia in Babies

Tracheomalacia is a condition where the cartilage supporting the trachea (windpipe) is soft and floppy, causing the airway to partially collapse during breathing. This creates noisy breathing, a characteristic "barky" or "honking" cough, and sometimes wheezing. It can be congenital (present from birth) or acquired (often from prolonged intubation in premature babies). Most cases of congenital tracheomalacia improve as the cartilage strengthens with growth, typically by age 2-3.

Stridor (Noisy Breathing) in Babies

Stridor is a high-pitched, squeaky or whistling sound heard when a baby breathes in (and sometimes out). It is caused by narrowing or obstruction of the upper airway. The most common cause in infants is laryngomalacia (a floppy voice box), which is usually harmless and outgrown. However, stridor can also be caused by croup, vocal cord problems, airway malformations, or foreign body aspiration. New-onset stridor or stridor with breathing difficulty always needs medical evaluation.

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Frequently asked questions

Is subglottic stenosis (narrowed airway below vocal cords) normal?
Subglottic stenosis is a narrowing of the airway just below the vocal cords. It can be congenital (present from birth) or acquired, most commonly following prolonged intubation in premature or critically ill newborns. Symptoms include biphasic stridor (noisy breathing on both inspiration and expiration), recurrent or severe croup episodes, and exercise intolerance. Mild cases may be monitored as the child grows and the airway widens, while moderate to severe cases may require surgical intervention such as endoscopic dilation or open airway reconstruction.
When should I call the doctor about subglottic stenosis (narrowed airway below vocal cords)?
Your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care Your child turns blue, becomes extremely agitated, or is unable to speak or cry during a breathing episode -- call 911
When is subglottic stenosis (narrowed airway below vocal cords) normal?
Your child had mild croup once and recovered fully without complications A baby who was intubated briefly has no stridor or breathing difficulty after extubation Your child with known mild stenosis is growing well, feeding normally, and the stridor is stable or improving
What causes subglottic stenosis (narrowed airway below vocal cords)?
Subglottic stenosis is a narrowing of the airway just below the vocal cords. It can be congenital (present from birth) or acquired, most commonly following prolonged intubation in premature or critically ill newborns. Symptoms include biphasic stridor (noisy breathing on both inspiration and expiration), recurrent or severe croup episodes, and exercise intolerance. Mild cases may be monitored as the child grows and the airway widens, while moderate to severe cases may require surgical intervention such as endoscopic dilation or open airway reconstruction. Common explanations include: Your child had mild croup once and recovered fully without complications. A baby who was intubated briefly has no stridor or breathing difficulty after extubation.
What should I mention to my pediatrician about subglottic stenosis (narrowed airway below vocal cords)?
You should mention subglottic stenosis (narrowed airway below vocal cords) at your next visit if: Your child has had croup 3 or more times in a year, or croup episodes are unusually severe. Your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty. Your child has noisy breathing that is present both when breathing in and breathing out.
Is subglottic stenosis (narrowed airway below vocal cords) normal at 0-3 months?
Congenital subglottic stenosis may present with stridor from birth, while acquired stenosis typically develops days to weeks after extubation in a baby who was intubated in the NICU. The stridor is often biphasic, meaning it is heard during both breathing in and breathing out, which distinguishes it from laryngomalacia. If your baby was intubated and develops new-onset stridor, breathing difficulty, or feeding issues after extubation, your medical team will likely evaluate for subglottic stenosis with endoscopy.
Is subglottic stenosis (narrowed airway below vocal cords) normal at 3-12 months?
Mild congenital subglottic stenosis may become more apparent as your baby grows more active and breathes harder. A hallmark sign is recurrent croup, occurring more frequently than expected or being unusually severe. If your baby is diagnosed with croup more than 2-3 times in one season, or if croup requires hospitalization, your pediatrician may refer to a pediatric ENT to evaluate for underlying airway narrowing. Mild stenosis is often managed expectantly, as the airway grows and the relative narrowing improves.
Should I go to the ER for subglottic stenosis (narrowed airway below vocal cords)?
Seek emergency care if your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care, or if your child turns blue, becomes extremely agitated, or is unable to speak or cry during a breathing episode -- call 911. When in doubt, call your pediatrician's after-hours line for guidance.
Does subglottic stenosis (narrowed airway below vocal cords) go away on its own?
In many cases, subglottic stenosis (narrowed airway below vocal cords) resolves on its own, especially when your child had mild croup once and recovered fully without complications. By 3+ years, most children with mild to moderate subglottic stenosis outgrow their symptoms as the airway grows. Children who underwent surgical reconstruction typically do well, though long-term follow-up with an ENT specialist is important to monitor for restenosis. Some children may have a barky voice or mild exercise intolerance. After successful treatment, most children lead fully active lives without significant airway limitations.
AAPNIHAAO-HNS

References

  1. [1]American Academy of Pediatrics. Croup and Your Young Child. HealthyChildren.org. AAP
  2. [2]National Library of Medicine. Subglottic Stenosis. StatPearls, NIH. NIH
  3. [3]American Academy of Otolaryngology-Head and Neck Surgery. Pediatric Airway Disorders. AAO-HNS

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Subglottic Stenosis (Narrowed Airway Below Vocal Cords).

Things to mention

  • Describe when you first noticed subglottic stenosis (narrowed airway below vocal cords) and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if your child has had croup 3 or more times in a year, or croup episodes are unusually severe.
  • Mention if your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • Your child has had croup 3 or more times in a year, or croup episodes are unusually severe
  • Your baby who was intubated in the NICU has persistent noisy breathing or feeding difficulty
  • Your child has noisy breathing that is present both when breathing in and breathing out

Urgent signs to report immediately

  • Your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care
  • Your child turns blue, becomes extremely agitated, or is unable to speak or cry during a breathing episode -- call 911

My notes

From ismybabyalright.com — free, evidence-based baby health guides

All content follows our editorial policy and is reviewed against published clinical guidelines.

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Related Resources

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Bottom line

Most cases of subglottic stenosis (narrowed airway below vocal cords) are normal. Talk to your pediatrician if your child has severe stridor at rest with chest retractions, nasal flaring, or difficulty breathing -- seek emergency care.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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Related Medical Concerns

Laryngomalacia (Floppy Airway)

Laryngomalacia is the most common cause of noisy breathing (stridor) in infants. It occurs when the tissue above the vocal cords is unusually soft and floppy, causing it to collapse inward during breathing and create a high-pitched squeaky sound. It typically appears within the first 2 weeks of life, peaks in severity at 4-8 months, and resolves on its own by 12-18 months. Most cases are mild and require no treatment beyond monitoring.

Tracheomalacia in Babies

Tracheomalacia is a condition where the cartilage supporting the trachea (windpipe) is soft and floppy, causing the airway to partially collapse during breathing. This creates noisy breathing, a characteristic "barky" or "honking" cough, and sometimes wheezing. It can be congenital (present from birth) or acquired (often from prolonged intubation in premature babies). Most cases of congenital tracheomalacia improve as the cartilage strengthens with growth, typically by age 2-3.

Stridor (Noisy Breathing) in Babies

Stridor is a high-pitched, squeaky or whistling sound heard when a baby breathes in (and sometimes out). It is caused by narrowing or obstruction of the upper airway. The most common cause in infants is laryngomalacia (a floppy voice box), which is usually harmless and outgrown. However, stridor can also be caused by croup, vocal cord problems, airway malformations, or foreign body aspiration. New-onset stridor or stridor with breathing difficulty always needs medical evaluation.

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Achondroplasia (Dwarfism) in Babies

Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.

Adenoid Hypertrophy and Breathing

Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.