The impact of human milk on necrotizing enterocolitis: A systematic review and meta-analysis

Background. Premature infants receiving breastfeed have a lower incidence of NEC than those fed preterm formula. This study aimed: (1) to update a systematic review and meta-analyses to evaluate the relationship between feeding and necrotizing enterocolitis (NEC) in low weight premature infants; (2) to conduct meta-regression analyses by subgroups; (3) to describe geographical distribution of milk banks in the world. Methods. Papers included in the meta-analysis were updated as of June 2019. Relative risks were used as a measure of effect size. Random effect models were used to account for different sources of variation among studies. For milk banks, the data reviewed by the literature were integrated with the information collected from countries’ institutional sites and milk bank networks. Results. Thirty-two papers were included in meta-analysis: six randomized controlled trials (RCTs) and 26 observational studies (OS). The census has found 572 milk banks around in the world. Brazil has the most active milk banks. RCTs meta-analysis indicates a risk reduction of NEC using human milk respect to formula: Relative risk (RR) = 0.62 (0.42–0.93). Seven OS compared quantities lower than human milk or higher than the 50th quantile showing a risk reduction of NEC:RR = 0.51 (0.31–0.85); 3 OS that evaluated human milk versus mixed feeding showing that human milk has a protective role on the development of NEC:RR = 0.74 (0.63–0.91). Results of subgroups analysis show that the risk reduction is statistically significant only for studies in which premature infants are given both their own and donated breastmilk. Conclusions. The possibility of preserving human milk and promoting donations guarantees an improvement in the health of newborns.