Stridor (Noisy Breathing) in Babies
The short answer
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.
By Age
What to expect by age
Stridor that is present from birth or develops in the first weeks of life is most commonly caused by laryngomalacia, where the tissue above the vocal cords is floppy and collapses inward during breathing. This is usually worse when the baby is on their back, crying, feeding, or congested. Laryngomalacia is typically diagnosed clinically and resolves by 12-18 months. Rarely, stridor from birth may indicate a more serious airway abnormality requiring further evaluation.
Stridor from laryngomalacia often peaks in severity around 4-8 months of age. If your baby's stridor is getting louder, this is often part of the natural course as the baby breathes harder and faster during growth spurts and increased activity. However, if stridor is accompanied by poor feeding, choking episodes, poor weight gain, apnea, or color changes, an ENT evaluation with flexible laryngoscopy may be recommended.
Laryngomalacia should begin improving around this age. If stridor persists or worsens beyond 8-9 months, or if your baby has significant feeding difficulties or failure to thrive, further investigation may be needed. Other causes of stridor at this age include subglottic stenosis (narrowing below the vocal cords), hemangiomas of the airway, or vocal cord paralysis. Croup can also cause acute stridor with its characteristic barky cough.
Most laryngomalacia resolves by 12-18 months. New stridor in a toddler is more likely to be caused by croup (viral laryngotracheitis), which presents with a barky cough and worsens at night. Sudden onset of stridor without illness in a toddler should raise concern for foreign body aspiration. If your toddler suddenly develops stridor while eating or playing with small objects, seek emergency care immediately.
What Should You Do?
When to take action
- Baby has mild inspiratory stridor that is worse when lying down or congested and has been present since birth (likely laryngomalacia)
- Stridor improves when baby is placed on their stomach or in an upright position
- Baby is feeding well, gaining weight, and having no color changes despite the noisy breathing
- Stridor has been gradually improving as the baby gets older
- Baby has persistent stridor that has not been evaluated by a doctor
- Stridor is getting louder or more frequent over weeks
- Baby is having feeding difficulties, choking, or slow weight gain along with stridor
- Baby suddenly develops stridor with significant breathing difficulty, chest retractions, or color changes -- call 911
- Toddler develops sudden stridor while eating or playing (possible foreign body aspiration) -- call 911 immediately
Sources
Related Resources
Related Medical Concerns
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
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.
Air Quality and Baby Health
Babies and young children are more vulnerable to air pollution than adults because they breathe faster, their lungs are still developing, and they spend more time close to the ground where some pollutants concentrate. The EPA recommends keeping babies indoors when the Air Quality Index (AQI) exceeds 100 (orange level). During wildfire smoke events, keep windows closed, use air purifiers with HEPA filters, and monitor your child for coughing, wheezing, or difficulty breathing. Long-term exposure to air pollution can affect lung development.
Altitude Sickness in Babies
Babies and toddlers can experience altitude sickness when traveling above 5,000-8,000 feet (1,500-2,500 meters). Symptoms are harder to recognize in infants because they cannot describe how they feel. Watch for unusual fussiness, poor feeding, disrupted sleep, vomiting, and fast breathing. Gradual ascent is the best prevention. Most pediatricians recommend avoiding sleeping at very high altitudes (above 8,000 feet) with infants when possible, and descending immediately if symptoms appear.
Amblyopia (Lazy Eye) Treatment Timing
Amblyopia (lazy eye) is the most common cause of vision loss in children, affecting 2-3% of the population. It occurs when one eye develops weaker vision because the brain favors the other eye. Early detection and treatment are critical because the visual system is most responsive to treatment during early childhood. Treatment is most effective when started before age 7, though improvement is possible at older ages. Treatment options include patching the stronger eye, atropine eye drops, glasses, or a combination.