What condition was most likely responsible for the premature infant's severe breathing difficulty?

The condition most likely responsible for the premature infant's severe breathing difficulty is Respiratory Distress Syndrome (RDS). This condition is particularly prevalent in premature infants due to their underdeveloped lungs and insufficient surfactant, a substance that helps keep the alveoli (air sacs in the lungs) open for gas exchange. Without adequate surfactant, the infant struggles to breathe effectively, leading to the classic symptoms of RDS, which include rapid, labored breathing and grunting during expiration.

In premature infants, the risk of RDS increases significantly because surfactant production typically begins around 24 to 28 weeks of gestation, with sufficient levels usually reached by about 34 to 36 weeks. Thus, those born before this gestational age are at a higher risk for severe breathing difficulties due to this syndrome. Although other conditions can contribute to respiratory issues in neonates, RDS is a direct consequence of prematurity and lung immaturity, making it the most likely cause of severe difficulty in this context.