Seppo AE, et al. - In this investigation, researchers studied the association of maternal probiotic supplementation with human milk oligosaccharides (HMOs), complex glycans and the third-largest solid component in human milk, concentrations. Depending on the mother’s Secretor and Lewis blood groups, the synthesis of HMOs involve the fucosyltransferases FUT2 (the Secretor gene) and/or FUT3 (the Lewis gene). This heterogeneity suggests non-exposure to certain structures of some breastfed infants, which may affect the composition of their microbiome and thus the risk of disease for diseases in which gut microbiome plays a role. Infants fed by mothers lacking a Secretor gene and therefore lacking a functional FUT2 enzyme, and all α-1-2-fucosylated oligosaccharides have delayed bifidobacteria-laden microbiota development. They also have a higher risk of manifesting IgE-associated eczema if these infants are born through cesarean delivery. Throughout lactation, changes in HMO abundance were seen. It is noted that certain HMOs are associated with cow-milk allergy protection in infants.