This research project is based on the notion that modulation of early microbial contact by probiotics may provide a safe and effective means to improve the health of preterm infants. In particular, the investigators hypothesize that the protective potential of probiotics may be enhanced via breast milk by administering probiotics to the lactating mother. All of the potentially beneficial effects of probiotic bacteria are strain-specific and therefore preliminary laboratory and clinical research with regard to different physiological targets of probiotic intervention should be carried out to guide the design of large-scale clinical trials aiming show clinical efficacy and establish clinical practice. The purpose of this research project is to identify targets for probiotic therapy in premature neonates and to provide insight into the optimal probiotic strains and administration protocol the clinical efficacy of which will subsequently be tested in a randomized controlled trial.