Probiotics in Term Infants: Clinical Impact of Infant-Type Bifidobacteria: A Systematic Review and Meta-analyses.

Probiotics labeled "infant-type bifidobacteria" (ITB), such as the B. longum subsp. infantis strains, have gained significant attention in recent years for their potential to positively influence the gut microbiome, early immune system development, and consequently future health. However, significant knowledge gaps remain regarding the actual clinical impact, the optimal strains, dosing regimens, and treatment duration-both in general and for ITB-probiotics specifically. This systematic review evaluates the clinical effects of administering ITB-probiotics to healthy, term infants within the first year of life. The aim was to address all categories of clinical outcomes. However, the included studies focused primarily on antibiotic use, atopic conditions, gastrointestinal health, and growth. We systematically and comprehensively searched PubMed, Embase, CENTRAL, and Scopus, followed by a meta-analysis where applicable. A total of 25 studies were included and assessed for risk of bias using the revised Cochrane tool (RoB 2). We found that early administration of ITB-probiotics was associated with a significant reduction in eczema [risk ratio (RR) = 0.78 (0.68, 0.90)] and a borderline significant reduction in respiratory tract infections [RR = 0.74 (0.54, 1.00)]. Other commonly reported outcomes, including antibiotic use, diarrhea, asthmatic bronchitis, and food allergy, also showed trends toward a preventive effect, though these findings did not reach statistical significance. This review underscores the potential clinical relevance of ITB-probiotics, particularly in the prevention of eczema and respiratory tract infections. However, the evidence is limited by study heterogeneity and a lack of long-term follow-up data. Further high-quality randomized controlled trials with larger sample sizes and standardized outcome measures are needed to clarify both short- and long-term effects of ITB probiotic administration in neonates and infants. This trial was registered at PROSPERO as CRD42024507608.