Epidemiology of Necrotising Enterocolitis

Necrotising enterocolitis is a rare disease with an overall incidence reported in the range of 0.5–5.0 per 100,000 live births. This is a broad range and most likely the true incidence lies towards the lower end of this estimate when more precise definitions are used. The incidence varies across the world with many countries and populations having a recognised higher incidence, whilst others have a lower incidence. The vast majority of cases of NEC are found in babies born prematurely with an inverse relationship between gestational age and NEC risk: the most premature babies are at the highest risk. In term babies, NEC is almost always associated with specific risk factors, most commonly congenital cardiac disease. In both premature babies and those born at term there are multiple risk factors that have been identified. The most important of these is enteral feeding and especially the type of feed. Cows’ milk-based formula confers a much higher risk of NEC than human milk. Other factors include birth trauma, sepsis and anaemia.