Epidemiologic study of necrotizing enterocolitis among low-birth-weight infants. Absence of identifiable risk factors.

Necrotizing enterocolitis has been associated with a variety of perinatal problems which have been purported to be risk factors predisposing the neonate to NEC. The present investigation compares the perinatal histories of 48 low-birth-weight infants (less than 1,500 gm) with NEC to those of 553 high-risk infants of equivalent birth weight who did not have NEC but who were present in the nursery during a four-year observation period. The two populations were equivalent with regard to maternal factors such as socioeconomic status, education, race, and age. Both the antenatal and intrapartum risk scores were similar, as were the position of presentation and mode of delivery. The incidence of pre-eclampsia, prolonged rupture of the membranes, and placenta previa was also equivalent. Birth weight and gestational age were identical, as well as intrauterine growth retardation and low Apgar scores. The placement of umbilical artery catheters or the performance of exchange transfusions were not more frequent among patients with NEC. Infants who developed NEC demonstrated significantly different incidences of only three variables. Mothers of these infants were usually married, and their infants had less respiratory distress syndrome; the only adverse factor present more frequently was abruptio placenta. These data raise further questions concerning the significance of previously reported risk factors of NEC.