Exploring the Relationship Between Maternal Psychological Factors and IgA Levels in Breast Milk: A Scoping Review.

BACKGROUND: Secretory immunoglobulin A (IgA) is the predominant immunoglobulin in human milk and a key component of neonatal mucosal immunity. While its biological functions are well established, the impact of maternal psycho‑emotional factors on its concentration remains largely unknown. No previous review has systematically mapped this intersection. OBJECTIVES: To synthesize evidence on relationships between maternal psycho-emotional factors-depression, anxiety, stress, fatigue, and sleep disturbance-and IgA concentrations in human milk. METHODS: Following the JBI framework and PRISMA-ScR guidelines, a comprehensive search was conducted across MEDLINE, Embase, Cochrane, CINAHL, PsycINFO, Scopus, and Web of Science without date restrictions. Fourteen studies met eligibility criteria. Data were extracted using a standardized form and synthesized narratively. RESULTS: Findings were heterogeneous, with positive, negative, and null associations across psychological domains. Occasionally, anxiety was associated with lower milk IgA in early postpartum cohorts, whereas associations with depressive symptoms varied by lactation stage. Postpartum-specific stress showed the clearest inverse relationship with milk IgA, although evidence remained limited. Only one study assessed maternal fatigue, and none examined sleep disturbance. Differences in lactation stage, milk sampling timing, and laboratory methods appeared to contribute substantially to variability across studies. CONCLUSION: Maternal psycho-emotional factors do not exert a uniform influence on milk IgA. Instead, evidence suggests context-dependent patterns shaped by lactation stage, biological processes, and methodological factors. This review highlights an understudied area and underscores the need for standardized longitudinal studies to clarify how maternal mental health interfaces with lactational immunity.