• The effect of probiotic supplementation on the intestinal microbiota of premature infants
  • Hanie Baghnavi,1,* Zeinab Ghoddousi,2 Mehri Tahsini Roudi,3
    1. Nutrition and Food Security Research center, Mashhad University of Medical Sciences, khaf, Iran
    2. Nutrition and Food Security Research center, Mashhad University of Medical Sciences, Mashhad, Iran
    3. Nutrition and Food Security Research center, Mashhad University of Medical Sciences, khaf, Iran


  • Introduction: According to the World Health Organization (WHO) data, more than 10 percent of babies are premature every year. Birth prior to 37 weeks of gestation is considered preterm. This Organization further classified preterm infants as 3 groups includes: Extremely preterm (under 28 weeks of gestation), Very preterm (28 through 31 weeks), Moderate preterm (32 through 33 weeks),Late preterm( 34 to 36 weeks). Preterm infants with a gestational age of under 32 weeks have a higher risk of mortality, with a survival rate of less than 80% before discharge from the hospital. Therefore, appropriate treatment in the early life of premature infants is of great importance to reduce complications and promote the survival rate of them. Premature babies have an underdeveloped immune system that puts them at risk for diseases such as necrotizing enterocolitis (NEC) and sepsis. As a result, premature babies admitted to the neonatal intensive care unit (NICU) are prescribed extensive antibiotics due to these risks. On the other hand, many past studies have shown that the composition of the intestinal microbiota of infants affects the growth and development of children, and that disruption of its composition causes various diseases such as necrotizing enterocolitis of infancy, childhood obesity, asthma, high blood pressure, diabetes, and other adult diseases. Antibiotics may alter the gut microbiota of premature babies. In this study, whether the use of probiotic supplements can improve the gut microbiota of premature babies, is investigated.
  • Methods: A literature search was performed in PubMed and Medline databases for randomized controlled trials, cohort, and case-control studies published up to 2025. Studies that assessed probiotic supplementation in preterm infants (<37 weeks) and reported gut microbiota composition were included.
  • Results: In all studies, feces from premature and term infants were collected during the first and last days of probiotic supplementation, and were examined for the types of microbes present in the normal flora. All the studies confirm, in the first days of the period, the relative abundance of Bifidobacterium, Bacteroides and Lactobacillus were lower in the feces of premature infants, and the relative abundance of Acinetobacter, Escherichia and Clostridium was higher. After a period of 28 to 30 days of supplementation, with probiotics containing lactobacillus and Bifidobacterium, studies showed in the supplemented group compared to the group that did not receive the supplement, the relative frequency of Enterococcus and Enterobacter were higher and the relative frequency of Escherichia and Clostridium were lower. Furthermore, premature infants who received the probiotic supplement earlier had higher weight-for-height ratios than those who received the supplement later.
  • Conclusion: Probiotic supplementation can reduce the relative abundance of potentially pathogenic bacteria and increase the abundance of beneficial microbiota in premature infants, but the supplemented microbes cannot become the dominant microbiota of premature infant’s microflora. Further high-quality clinical trials are needed to determine optimal strains, doses, and timing.
  • Keywords: Premature Birth, Probiotics, GI Microflora, Feces