A new RCT in more mature preterm infants 32 to 37 weeks compared the incidence of viral respiratory infections during the first year of life between infants who received prebiotics (galacto-oligosaccharide and polydextrose) probiotics (lactobacillus rhamnosus) or placebo between the 3rd and the 60th days of life. Luoto R, Ruuskanen O, Waris M, Kalliomaki M, Salminen S, Isolauri E. Prebiotic and probiotic supplementation prevents rhinovirus infections in preterm infants: a randomized, placebo-controlled trial. The Journal of allergy and clinical immunology. 2014;133(2):405-13.
There were only just over 20 in each group that completed the follow up period, but there was a significant reduction in total respiratory infections, and particularly in rhinovirus infections. The prebiotic group did better than the probiotic group, but both had a significant reduction in rhinovirus and overall respiratory infections than the controls, over the first year of life.
The authors include a systematic review of previous studies in the discussion, of either prebiotics or probiotics or both: of the 7 previous studies (in full term infants) 5 have shown a reduction in respiratory infections, for some reason 3 of the previous studies were from Finland, including the largest which had 1000 babies enrolled (and showed a reduction in respiratory infections).
Maybe we shouldn’t be limiting our probiotics to just the early preterms, the late preterms may have advantages too!