Trimester-Specific Air Pollutant Exposure During Pregnancy and Infant Neurodevelopment at One Year: Insights into the Role of Inflammation and Oxidative Stress

Prenatal exposure to air pollution is a major public health concern due to its potential to impair fetal brain development. This study examined whether maternal inflammatory and oxidative stress biomarkers mediate the association between trimester-specific air pollutant exposure during pregnancy and infant neurodevelopment at one year. We analyzed 87 mother–infant pairs from the OBESO perinatal cohort in Mexico City. Trimester-specific exposure to CO, PM10, PM2.5, SO2, and O3 was estimated using residential geolocation. Biomarkers were measured in the first and third trimesters by protocol, and intra-pregnancy change was calculated as Δ(3T–1T) for cytokines (IL-1β, IL-6, TNFα) and oxidative stress markers (malondialdehyde (MDA), protein carbonyls (PC), and total antioxidant capacity (TAC). Infant neurodevelopment at 12 months was assessed using Bayley-III. Exploratory mediation analyses were conducted, adjusting for gestational age at birth, pre-eclampsia, gestational diabetes, fetal growth restriction, marital status, mode of delivery, and infant sex; bootstrapping was applied to obtain robust estimates. Third-trimester CO exposure was associated with poorer receptive language (coef = 0.754, p = 0.02). PM2.5 exposure showed direct effects on expressive language in the first (coef = 0.01, p = 0.04) and third trimesters (coef = 0.007, p = 0.015) in models including IL-1β. Third-trimester O3 and SO2 exposures were linked to lower expressive scores in models including TNFα (coef = 0.007, p = 0.02), MDA (coef = 0.008, p = 0.04), and PC (coef = 0.007, 95% p = 0.04). Meanwhile PM10 exposure was associated with socio-emotional outcomes in models with IL-6 and TAC (coef = 0.003, p = 0.04). These findings indicate that maternal inflammation and oxidative stress biomarkers did not mediate the associations between prenatal air pollution exposure and infant neurodevelopment, and this study cannot elucidate their specific biological role in neurodevelopment.