Maternal Cannabis Use and Secretory IgA and IgM Concentrations in Breast Milk.

Moshtagh C.; Hernandez Galan L.; Mbuagbaw L.; Raha S.; Ratcliffe E.; Shea A. · Breastfeeding medicine : the official journal of the Academy of Breastfeeding Medicine · 2026

**Background & Methods** This prospective cohort study enrolled 160 pregnant and lactating women (110 controls and 50 cannabis users) between January 2023 and December 2024 to examine associations between maternal cannabis use patterns and secretory immunoglobulin A (SIgA) and IgM (SIgM) concentrations in breast milk. Mature breast milk samples were collected 4-16 weeks postpartum and analyzed for five cannabinoids (Δ9-tetrahydrocannabinol, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol, 11-hydroxy-Δ9-tetrahydrocannabinol, cannabinol, and cannabidiol) with subsequent SIgA and SIgM quantification. **Key Findings** • Maternal age was the characteristic most consistently associated with breast milk immunoglobulin concentrations; increasing maternal age was associated with significantly lower SIgA and SIgM levels (p < 0.05). • Cannabis users who also consumed nicotine demonstrated higher SIgA levels compared to controls (1.27 versus 0.60 g/L; p = 0.002), but this elevation was substantially attributable to concurrent nicotine use rather than cannabis alone. • Cannabis-only consumers did not show significant differences in SIgA concentrations compared to controls (p = 0.094), and cannabis users were demographically younger, had lower educational levels, and higher parity than nonusers. **Dosage & Administration** Not reported. The study analyzed cannabinoid concentrations present in breast milk samples but did not specify maternal cannabis dosage, frequency, route of administration, or timing of use relative to lactation. **Safety & Adverse Effects** Not reported. The study did not assess or report adverse effects in infants or mothers, nor did it evaluate potential clinical consequences of detected cannabinoid or immunoglobulin concentrations. **Evidence Quality** This review-type publication has several limitations. The modest sample size (50 cannabis users) limits statistical power and generalizability. Inability to separate cannabis from co-occurring substance use (particularly nicotine) confounds interpretation of cannabis-specific effects. Sociodemographic differences between users and controls (age, education, parity) may introduce additional confounding. The clinical significance of observed immunoglobulin differences remains unknown. The authors acknowledge that larger studies with better separation of individual substance use patterns are necessary to clarify the true association between maternal cannabis use and breast milk immune factors. This represents preliminary evidence requiring substantial additional investigation.

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