A total of 926 preterm infants were studied, 51 of whom developed nectrotising enterocolitis (NEC). Exclusively formula-fed infants were 6 to 10 times more likely to develop NEC than those who received breastmilk. Although NEC is rare in babies over 30 weeks gestation, it was 20 times more common if the baby had received no breastmilk.
Lucas A & Cole TJ (1990). Breast milk and neonatal necrotising enterocolitis. Lancet 336: 1519-1522. [Abstract]