Inclusion Criteria:  Infants up to and including four days of age* Infant delivered at a study hospital Orally feeding currently** Informed consent by parent or guardian Intends to maintain residence within the defined catchment areas (upon discharge from hospital) until 60 days of age.  Exclusion Criteria:  Birthweight < 1500 grams*** Death or major surgery considered to be highly probable within first week of life**** Major congenital anomaly of the gastrointestinal tract Maternal HIV infection and/or history of mother ever receiving anti-retroviral drug(s) for presumed HIV infection***** Current mechanical ventilation and/or cardiac support (e.g., inotropes) and/or administration/prescription of parenteral antibiotics* Any prenatal or postpartum use of non-dietary probiotic supplement by mother during current pregnancy****** Any postnatal administration of non-dietary probiotic or prebiotic supplements to infant Current participation of the infant in another clinical trial Resides in the same household as another infant previously enrolled in the study, or any study within the research platform, who is currently <60 days of age; however, twins may all be enrolled simultaneously in this trial. Multiple gestation for which the number of liveborn infants from the same pregnancy exceeds two (i.e., triplets or higher order multiples).  '*Day of birth is considered day 0 of life. Therefore, the infant could be enrolled on days 0, 1, 2, 3 or 4 of life.  '**These criteria are time-varying, so will be reassessed on a daily basis until no longer eligible for another reason (i.e., beyond day 4 of life) as long as the infant remains potentially eligible by other criteria. Orally feeding is defined as being able to take a probiotic or synbiotic supplement by mouth on a daily basis.  '***Current infant weight, as measured and documented by study personnel, will be used if birth weight is missing, illegibly recorded, or suspected of being an error (e.g., implausible value, discrepancy of greater than 15% between documented birth weight and measured screening weight).  '**** Major surgery as an operative procedure to explore and/or repair an organ or tissue that is performed under general anaesthesia. Examples relevant to the neonatal period include: ligation of patent ductus arteriosus, repair of abdominal wall defects, repair bowel perforation due to of necrotizing enterocolitis, repair of tracheoesophageal fistula and/or esophageal atresia, and repair of myelomeningocele. Conversely, examples of common procedures in newborns not considered major surgery include circumcision, tongue tie release, removal of extra digit (polydactyly).  '*****Although HIV in very young infants will be rare in this context, there is a low but non-zero theoretical risk that a baby born to an HIV positive mother could be significantly compromised, particularly in cases where in utero transmission occurred earlier in pregnancy. Both the HIV positive mother and infant are expected to represent a unique population in regards to their respective microbiomes, and excluding them should not affect generalizability of results to the population as a whole. The number of HIV positive infants is anticipated to be too low to conduct sub-group analyses and thus, it would not be possible to make meaningful inferences about this population, even if they were to be included in the study. Testing for HIV infection will not be performed as a study procedure; therefore, this criterion will be based on information available from the medical record.  '******Non-dietary probiotic supplement is a commercial (store-bought) probiotic product that is consumed in the form of a capsule, powder, liquid, etc., although it may be mixed into a food or drink at the time of consumption. In contrast, a dietary probiotic is an ingredient of a food or beverage that either occurs naturally or is added during home production or the commercial manufacturing process (e.g., yoghurt or fermented drinks).