How many infants are affected by or at risk of necrotizing enterocolitis (NEC)?

According to a 2008 review of the evidence, all newborn infants born preterm (before 37 weeks of pregnancy) or born with a low birth weight (less than 2,500 grams, or about 5.5 pounds) are at increased risk for NEC. The smaller the infant or the more premature the delivery, the greater the risk.1

NICHD estimates that NEC affects about 9,000 of the 480,000 infants born preterm each year in the United States.2,3

The population most at risk for NEC is increasing because with technological advances in care the number of very low birth weight infants who survive continues to grow.1 The percentage of very low birth weight infants who develop NEC remains steady, however, at about 7%.1

NEC continues to be one of the leading causes of illness and death among preterm infants.4 Fifteen to forty percent of infants with NEC die from the disease.1,3

Although NEC mostly occurs in preterm infants, it occasionally occurs in infants born at term. One study found that about 9% of all NEC cases that occurred in one children’s hospital over 30 years were in full-term infants.5 Full-term infants with NEC often have another serious illness or risk factor, such as congenital heart disease or restricted growth in the womb. NEC may also have a different disease process in full-term versus preterm infants.1


  1. Lin, P. W., Nasr, T. R., & Stoll, B. J. (2008). Necrotizing enterocolitis: Recent scientific advances in pathophysiology and prevention. Seminars in Perinatology, 32, 70–82.
  2. Hamilton, B. E., Martin, J. A., & Ventura, S. J. (2011). Births: Preliminary data for 2010. National Vital Statistics Reports, 60(2), 1–25. Retrieved August 1, 2012, from (PDF 460 KB)
  3. NICHD. (2010). Small protein provides target to help prevent potentially lethal condition [news release]. Retrieved August 1, 2012.
  4. Thompson, A. M., & Bizzarro, M. J. (2008). Necrotizing enterocolitis in newborns: Pathogenesis, prevention and management. Drugs, 68, 1227–1238.
  5. Ostile, D. J., Spilde, T. L., St Peter, S. D., Sexton, N., Miller, K. A., Sharp, R. J. (2003). Necrotizing enterocolitis in full-term infants. Journal of Pediatric Surgery, 38(7), 1039–1042.
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