It is recognized that the health of preterm babies benefits greatly from the ingestion of their mothers own breastmilk due to a number of factors including the presence of active enzymes that enhance the maturation of the underdeveloped gut, anti-infective properties which protect the newborn from infection and earlier tolerance of full enteral feeding. As donor milk is usually provided by women who deliver at term, and is pasteurised, the authors argue that it cannot be presumed that it will have the same effect as mothers’ own breastmilk. The aim of this systematic review, therefore, was to compare the effects of pasteurised donor breast milk and infant formula in preterm infants.

Seven studies were found to comply with the inclusion criteria, although methodological weaknesses were present in all. Six looked at the impact of donor breastmilk on necrotizing entero-colitis (NEC) and the combined evidence from these studies suggests that donor milk reduces the risk of NEC by about 79%. The other main outcome measure of growth had mixed findings with more studies finding in favour of formula in terms of infant growth. One study however, tracked growth at 9 and 18 months and 7-8 years at which times no significant differences in a range of growth measurements were found. Importantly, this study found significantly slower growth in the donor milk group compared with the formula group during the early postnatal period. The authors suggest that further research is needed to confirm their findings and measure the effect of donor breast milk that is fortified or given as a supplement to mother’s own milk.

In response to the Boyd paper (above) Williams et al make a number of useful comments in a perspective published in the same journal.

• Given the incidence of preterm birth, the paucity of data in this area is disappointing. Despite this Boyd et al were able to clearly demonstrate that formula-fed very low birthweight babies are at significantly increased risk of necrotising enterocolitis (NEC) compared with those fed exclusively on breast milk.
• The ongoing high incidence of NEC and related mortality and severity of morbidity among survivors make this finding important. The recent eleventh annual report of the British Paediatric Surveillance Unit cited an incidence of 2.1/1000 neonatal unit admissions, 65% of whom weighed under 1500 g at birth. Overall mortality was 22% but it was significantly lower in those fed human milk compared with those fed on formula (5% v 26%, p<0.05).
• Remarkably, despite large differences in early rates of growth seen in the neonatal unit, no anthropometric differences were observed at school age, even in the group fed donor breast milk as sole diet.¹
• They recommend setting up a national network of milk banks as this would enable greater cost-effectiveness and quality control together with affording the opportunity for further research into this important area.