The Bloom Infant Probiotic (BIP) Study

Inclusion Criteria: 1. Infants administered antibiotics in the first 28 days of life. Infants must have documented direct antibiotic exposure - defined as having received at least 36 hours of antibiotic treatment in the neonatal period (the first 28 days after birth). 2. Gestational age ≥ 35 weeks. 3. Birth weight ≥ 2500g. 4. Mother aged at least 18 years and able and willing to provide written informed consent for themselves and their infant. 5. Parent/guardian agrees to not give any other probiotics to their infant prior to vaccination at 6 weeks, including any formula that contains probiotics. 6. Infant planning to receive all nationally approved vaccines during next 6 months. Exclusion Criteria: 1. Significant medical condition in either the mother or infant that, in the opinion of a medical investigator, may interfere with the study. 2. Infant had confirmed sepsis or other serious infection in the neonatal period. 3. Infants with known congenital diseases or who are immunocompromised or considered medically at risk (MAR). 4. Infant participating in another interventional trial during the trial period.