At birth, the baby’s immune system is still immature. A protective commensal gut microbiota is one of the key factors responsible for the maturation of the baby’s immune system. Breastfeeding is known to establish beneficial gut microbiota in infants.1-3\r\rReferences:\r\r\r Martin R, Nauta AJ, Ben Amor K, Knippels LM, Knol J, Garssen J. Early life: gut microbiota and immune development in infancy. Benef Microbes. 2010 Nov;1(4):367-82.\r Walker WA. Intestinal colonization and programming of the intestinal immune response. J Clin Gastroenterol. 2014 Nov-Dec;48 Suppl 1:S8-11.\r Rodríguez JM, Murphy K, Stanton C, Ross RP, Kober OI, Juge N et al. The composition of the gut microbiota throughout life, with an emphasis on early life. Microb Ecol Health Dis. 2015 Feb;26:26050.