Which of the following is the commonest cause of stridor in a newborn who born at term?
**Core Concept**
Laryngomalacia is a condition characterized by the softening of the tissues of the larynx (voice box) in infants, leading to partial airway obstruction. This condition is the most common cause of stridor in newborns, resulting from the collapse of the supraglottic airway during inhalation.
**Why the Correct Answer is Right**
Laryngomalacia typically presents within the first few weeks of life, with symptoms such as stridor, feeding difficulties, and respiratory distress. The condition is often associated with a redundant epiglottis and aryepiglottic folds, which can cause partial airway obstruction. In many cases, laryngomalacia resolves spontaneously by the age of 12-18 months.
**Why Each Wrong Option is Incorrect**
**Option A:** Vocal cord paralysis is a possible cause of stridor in newborns, but it is less common than laryngomalacia. Vocal cord paralysis typically results from injury to the vagus nerve or its branches during delivery.
**Option B:** Tracheomalacia refers to the softening of the tracheal cartilage rings, which can also cause stridor in newborns. However, tracheomalacia is less common than laryngomalacia and often presents with more severe respiratory distress.
**Option D:** Congenital laryngeal webs are rare congenital anomalies that can cause stridor in newborns. However, they are much less common than laryngomalacia.
**Clinical Pearl / High-Yield Fact**
Laryngomalacia is often associated with other congenital anomalies, such as cardiac defects and gastrointestinal anomalies. Therefore, a thorough evaluation is necessary to rule out other underlying conditions.
**Correct Answer:** C.