Background: Breast milk is the gold standard of infant nutrition, delivering nutrients and bioactive molecules as needed to support optimal infant growth and cognitive development. Increasing evidence links human milk oligosaccharides (HMOs) to these early childhood development milestones. Aims: To summarize and synthesize the evidence relating to HMOs and infant brain development, physical growth, and cognitive development. In addition, HMO concentrations in secretor and nonsecretor mothers were compared via a meta-analysis. Study Design: A systematic review and meta-analysis were carried out in accordance with the PRISMA statement. This review used three databases (PubMed, Scopus, and Web of Science) and was limited to English-language articles published between 2000 and June 30, 2023. Results: The initial searches yielded 245 articles, 27 of which were included in the systematic review and 12 in the meta-analysis. The meta-analysis revealed a substantial between-study heterogeneity, I2 = 97.3%. The pooled effect was 0.21 (95% CI: -0.41 to 0.83; p = 0.484), indicating that secretors had higher HMO concentrations, although this difference was not statistically significant. At one month of age, 2'FL, 3FL, and 3'SL play an important role in brain maturation and thus play a critical role in cognitive development. Secretors produce higher concentrations of 2'FL and 3'SL, explaining the benefits to infants of secretor mothers. Growth velocity was correlated to fucosylated and sialylated HMO concentrations, with lower concentrations linked to stunting. Conclusions: According to evidence from the systematically reviewed articles, HMOs are essential for a child's early development, but the extent to which they have an impact depends on maternal secretor status.
Keywords: brain development; breastfeeding; cognitive development; human milk oligosaccharides; infant growth; secretor.