Age at onset of necrotizing enterocolitis: an epidemiologic analysis.

We studied the epidemiologic interrelationships among birth weight, gestational age, and age at onset of necrotizing enterocolitis of the newborn. As birth weight increased, the range of ages at onset and the mean age at onset both decreased. Weekly birth weight-specific attack rates for necrotizing enterocolitis declined sharply in all birth weight groups when the equivalent of 35-36 wk gestational age was reached. Our data are consistent with the hypothesis that the risk period for necrotizing enterocolitis is determined primarily by the maturity of the gastrointestinal tract of the newborn.