Background A randomised, double-blind clinical trial was undertaken in order to assess the effectiveness of probiotics in the prevention of necrotising enterocolitis (NEC) in newborns weighing <1500 g.

Methods We studied a group of 150 patients who were randomised in two groups after parental consent was obtained, to receive either a daily feeding supplementation with a multispecies probiotic (Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus plantarum, Bifidobacteruim infantis, Streptococcus thermophillus) 1 g per day plus their regular feedings or to receive their regular feedings with nothing added (control group), over the period of January 2007 through June 2010. Clinicians in care of the infants were blinded to the group assignment.

Results The primary outcome was the development of NEC. Both groups were comparable, with no differences during hospitalisation, including the type of nutrition received. Blood cultures obtained from cases that developed sepsis did not reveal lactobacillus or Bifidobacteria growth. No differences were detected in terms of NEC risk reduction (RR: 0.54, 95% CI 0.21 to 1.39) although we did observe a clear trend in the reduction of NEC frequency in the studied cases: 6 (8%) versus 12 (16%) in the control group. When the combined risk of NEC or death was calculated as a post hoc analysis, we found a significantly lower risk (RR: 0.39, 95% CI 0.17 to 0.87) for the study group.

Conclusions Probiotics may offer potential benefits for premature infants and are a promising strategy in the reduction of the risk of NEC in preterm newborns.