When a baby makes a sound during breathing that resembles purring or a high-pitched squeak, parents often become concerned. This noisy breathing, medically termed stridor, is common in infancy because a baby’s airways are significantly narrower and more flexible than an adult’s. The small size and soft cartilage mean that even minor changes can produce noticeable sounds. Understanding the source helps parents determine whether the sound is benign or if it signals a need for medical attention.
Laryngomalacia The Primary Suspect
The most frequent cause of the purring sound in infants is Laryngomalacia (LM), which accounts for the majority of stridor cases. LM involves the supraglottic structures—the tissues surrounding the voice box—which are soft and floppy in newborns. During inhalation, these tissues, including the epiglottis, collapse inward, partially obstructing the airway opening.
This temporary blockage causes the air rushing past to create the noisy breathing heard upon inspiration. The condition is present from birth, often becoming louder around four to eight months as the infant moves air more vigorously. The sound tends to worsen when the baby is lying on their back, as gravity pulls the floppy tissues further over the airway.
The sound may also increase when the baby is agitated, crying, or feeding. Laryngomalacia is typically a benign, self-limiting condition that resolves without surgery. Most infants outgrow the condition as the laryngeal cartilage matures and stiffens, usually by 18 to 24 months old.
Other Common Causes of Respiratory Noise
While Laryngomalacia is the most common cause of inspiratory stridor, other conditions can also produce purring or rumbling respiratory sounds. Simple mucus or congestion in the upper airway creates a wet, gurgly noise as air bubbles through thick secretions. This noise is often loudest when the baby is lying down and is usually resolved by clearing the congestion.
Another related condition is Tracheomalacia, which involves the windpipe (trachea) instead of the voice box. In Tracheomalacia, the weak cartilage rings of the trachea cause the windpipe to collapse inward, especially during exhalation. This results in an expiratory wheeze, distinguishing it from the inspiratory sound of Laryngomalacia.
Common viral infections like Bronchiolitis or Respiratory Syncytial Virus (RSV) can also cause noisy breathing. These infections lead to inflammation and mucus buildup in the smaller airways, producing a dry, wheezy sound. The noise from infection is often accompanied by cold-like symptoms, such as a runny nose, cough, and fever.
Warning Signs Requiring Immediate Medical Attention
Although most causes of noisy breathing are harmless, parents must recognize signs indicating difficulty breathing, which requires immediate medical evaluation. The most important sign is an increased work of breathing, meaning the baby is exerting effort to get air. This includes retractions, where the skin visibly pulls in at the neck, between the ribs, or under the breastbone with each breath.
Nasal flaring, the widening of the nostrils during inhalation, indicates the baby is struggling to pull air in. Changes in skin color, especially a bluish tint around the lips or on the fingernail beds (cyanosis), signals a lack of sufficient oxygen. Any grunting sound made each time the baby breathes out is also a serious sign, as the body attempts to keep the lungs open.
Other concerning symptoms include an inability to feed or drink due to breathing effort, long pauses in breathing (apnea), or severe lethargy. If noisy breathing is accompanied by a high fever, or if the baby seems generally unwell, emergency medical assistance should be sought immediately.
Home Management and Comfort Measures
When a medical professional has ruled out a serious condition, parents can manage mild noisy breathing and congestion. Increasing air moisture helps thin mucus and soothe irritated airways. A cool-mist humidifier placed near the crib is effective for adding humidity.
For nasal congestion, saline nasal drops loosen thick mucus. Gentle suctioning with a bulb syringe or nasal aspirator safely removes the loosened secretions. This process is especially helpful 15 minutes before feeding or sleeping.
Positional changes often help alleviate the sound associated with Laryngomalacia. Since the sound is louder when a baby is on their back, holding the baby upright during and after feedings helps keep the airway open. Keeping the baby in a more upright or inclined position while awake may also reduce the collapse.