Newborn metabolomics linking prenatal air pollution exposure and autism spectrum disorder risk in children.

backgroundAutism spectrum disorder (ASD) is a major cause of childhood disability, and prenatal exposure to fine particulate matter (PM₂.₅) and traffic-related nitrogen oxides (NOₓ) has been associated with increased ASD risk. However, the biological mechanisms linking these exposures to ASD remain poorly understood.

objectiveTo identify neonatal metabolic pathways associated with prenatal exposure to PM₂.₅ and non-freeway NOₓ and their relevance to ASD risk using untargeted metabolomics.

methodsWe conducted a matched case-control study of 50 children diagnosed with ASD before age five and 50 controls, matched on birth year, sex, race/ethnicity, and medical center, from births at Kaiser Permanente Southern California (2007-2009). Prenatal PM₂.₅ and non-freeway NOₓ exposures were estimated using high-resolution spatial models based on residential histories. Metabolomic profiling was performed on newborn dried blood spots using a dual-platform LC-MS workflow: HILIC chromatography with positive ESI and C18 reversed-phase chromatography with negative ESI. We used conditional logistic and linear regression adjusted for matching factors and key child and maternal covariates to evaluate associations among metabolomic features, ASD, and prenatal air pollution. Pathway enrichment analyses were conducted using mummichog and MetaboAnalyst.

resultsAspartate and asparagine metabolism was significantly associated with ASD (p = 0.01), and with exposure to PM₂.₅ during the first trimester and entire pregnancy (p < 0.001), and non-freeway NOₓ (p = 0.003). Glutamate, nitrogen, and sialic acid metabolism pathways were also commonly associated with both ASD and air pollution. Key metabolites-including L-asparagine, GABA (4-aminobutanoate), succinate semialdehyde, and L-glutamine-were implicated in these pathways, suggesting a link to oxidative stress and inflammation. SIGNIFICANCE: This study reveals dysregulated neonatal amino acid metabolism as a potential mechanism 49 connecting prenatal air pollution exposure to increased ASD risk. High-resolution 50 metabolomics in newborns can provide critical insights into early-life environmental 51 influences on neurodevelopment and inform future etiological research on ASD. IMPACT STATEMENT: This study demonstrates that prenatal exposure to air pollution-specifically PM₂.₅ and non-freeway traffic-related NOₓ-is associated with dysregulated neonatal amino acid metabolism detectable in newborn blood. Using untargeted metabolomics, we identified shared pathways linking these exposures and autism spectrum disorder (ASD), particularly those related to oxidative stress and inflammation. These findings suggest a potential biological mechanism connecting environmental exposures in utero with later neurodevelopmental outcomes. Our results highlight the value of newborn metabolomics as a tool for early biomarker discovery and underscore the importance of reducing prenatal air pollution exposure to support healthy brain development.