Exposure to ambient air pollution during pregnancy and inflammatory markers in maternal and umbilical cord blood

Abstract

Background: Exposure to ambient air pollution during pregnancy has been associated with adverse pregnancy and birth outcomes. Inflammation has been proposed as a potential mechanistic link to explain this relationship. In a Colorado-based cohort, we estimated associations between air pollution exposure during pregnancy and inflammatory markers in maternal and cord blood. We also estimated associations between maternal inflammatory markers and infant birth and adiposity outcomes.Methods: Among 515 mother-infant dyads in the Healthy Start Study (2009-2014), trimester-specific and full pregnancy average concentrations of particulate matter of diameter ≤2.5 micrometers (PM2.5) and ozone (O3) were estimated using inverse-distance-weighted interpolation from stationary monitors. Inflammatory markers were measured in mid-pregnancy (median 27 weeks) maternal blood (CRP, IL-6, and TNFα) and cord blood at delivery (CRP, IL-6, IL-8, IL-10, MCP-1, and TNFα). Multivariable linear regression models estimated associations between PM2.5 and O3 exposure and inflammatory markers, and between maternal inflammatory markers and infant outcomes, including birth weight, gestational age at birth, and adiposity (percent fat mass) assessed via air displacement plethysmography.Results: Second trimester PM2.5 and first trimester O3 were positively associated with maternal IL-6 concentrations (PM2.5: 7.38% per IQR; 95%CI 1.40-13.72; O3: 8.09% per IQR, 95%CI 0.00-17.05). PM2.5 and O3 were positively associated with maternal TNFα (trimester 1: PM2.5: 10.77% per IQR; 95%CI 1.04-21.44; O3: 28.05% per IQR, 95%CI; 12.70-45.48; trimester 2: PM2.5: 9.19% per IQR; 95%CI 0.00-19.13, O3: 25.62% per IQR, 95%CI; 11.08-42.06). Ambient air pollution was not associated with inflammatory markers in cord blood. No consistent associations were found between maternal inflammatory markers and infant outcomes.Conclusions: We found evidence of a positive association between ambient air pollution exposure during pregnancy and maternal, but not cord blood, inflammatory markers. Further investigations should examine the health consequences for women of elevated inflammatory markers associated with air pollution exposure during pregnancy.