What is the etiology of NEC?

• A. It has a clearly defined single cause
• B. The etiology remains unclear, and NEC often occurs in infants being fed via the GI tract
• C. It is caused by a specific viral infection
• D. It is caused by overfeeding only

Answer: (B)

NEC is best understood as multifactorial rather than having a single, proven cause. In preterm or low birth weight infants, the gut is immature and more susceptible to injury. A combination of an immature intestinal barrier, altered blood flow to the gut, abnormal bacterial colonization, and an exaggerated inflammatory response can lead to intestinal inflammation and necrosis. Feeding via the GI tract, particularly formula feeding, is a known risk factor because it can expose the immature gut to more antigens and bacteria; breast milk, by contrast, has protective factors. Because no single pathogen or mechanism has been identified as the sole cause, the etiology remains unclear, and NEC often occurs in infants being fed enterally.