Which of the following is considered the MOST impoant risk factor for necrotizing enterocolitis?

Prematurity is the most impoant risk factor for necrotizing enterocolitis, although term infants also sometimes develop the condition. Clinical series have repoed that between 60 and 95% of affected babies are premature, and the incidence is markedly increased in babies born at lower gestational ages. Many other purpoed risk factors have also been cited but seem to have a lesser effect, including perinatal asphyxia, respiratory distress syndrome, umbilical catheterization, hypothermia, shock, patent ductus aeriosus, cyanotic congenital hea disease, polycythemia, thrombocytosis, anemia, exchange transfusion, congenital GI anomalies, chronic diarrhea, non-breast milk formula, nasojejunal feedings, hypeonic formula, and colonization with necrogenic bacteria. It may simply be that any already fragile baby, paicularly if premature, who has other significant underlying disease, is at increased risk for developing necrotizing enterocolitis. Ref: Thilo E.H., Rosenberg A.A. (2012). Chapter 2. The Newborn Infant. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.