Efficacy of Bifidobacterium breve and Lactobacillus casei oral supplementation on necrotizing enterocolitis in very-low-birth-weight preterm infants:a

http://www.ajcn.org/content/early/2010/10/27/ajcn.2010.29799.abstract
a double-blind, randomized, controlled trial
Design: A double-blind, randomized, controlled clinical trial was conducted in 231 preterm infants weighing from 750 to 1499 g at birth. The intervention group was composed of 119 infants who received human milk with probiotic supplementation (B. breve and L. casei) and a control group of 112 infants who received human milk containing no probiotics. The primary outcome was the occurrence of NEC stage ≥2 as defined by Bell's modified criteria.

Results: Four confirmed cases of NEC stage ≥2 by Bell's criterion occurred only in the control group.

Though the follow up is not mentioned in this article, they compared probiotic group with those receiving breast milk alone rather than with formula. That makes it interesting!