Fermented Foods, Functional Nutrition, and Maternal Gut Microbiota During Pregnancy: Molecular Mechanisms and the Maternal–Infant Microbiome Axis

Pregnancy is associated with profound metabolic, hormonal, and immunological adaptations accompanied by dynamic alterations in maternal gut microbiota composition and function. Emerging evidence suggests that maternal diet is a major regulator of these microbiota-related changes and may influence maternal-fetal health through microbial metabolites and host signaling pathways. Fermented foods and functional dietary components, including prebiotics, probiotics, synbiotics, and polyphenols, have gained increasing attention because of their potential to modulate gut microbial diversity, intestinal barrier integrity, inflammatory responses, and metabolic homeostasis. Mechanistically, these effects are mediated through pathways involving short-chain fatty acids, G protein-coupled receptors, nuclear factor kappa B signaling, histone deacetylase inhibition, and immune cell regulation. Altered microbiota-associated signaling has been linked to gestational metabolic disorders such as obesity, gestational diabetes mellitus, and preeclampsia, as well as fetal immune and metabolic programming. Particular emphasis is placed on the maternal-infant microbiome axis, highlighting how maternal nutrition and microbiota-mediated signaling may influence microbial transmission, fetal programming, and early-life microbiome development. This review summarizes current evidence regarding pregnancy-associated gut microbiota alterations and discusses the molecular mechanisms through which fermented foods and functional nutrition may influence maternal and fetal health outcomes.