The associations of maternal exposure to black carbon and foetal growth risks in Southern Sweden

Abstract

Black carbon (BC) is an air pollutant of emerging concern, and further evidence is needed to understand its health effects. This study investigates the association between gestational BC exposure and birth outcomes, and whether these effects are independent of particulate matter with an aerodynamic diameter of ≤ 2.5 μm (PM 2.5 ) exposure. We used data from the population-based birth cohort, Maternal Air Pollution in Southern Sweden (MAPSS) for the years 2000–2009, including 43,676 mother-child pairs. Maternal exposure to air pollution at residential address was estimated using a high-resolution dispersion model. We used logistic and linear regressions to examine association of air pollution with birth outcomes adjusting for maternal age, Body Mass Index, smoking, education, maternal country of birth, sex of the child, parity, household income, and birth year. We found that BC exposure during pregnancy was associated with birth weight (decrease of 69 g per 1 µg/m³ (95% Confidence Interval (CI): -96, -42) and small for gestational age (SGA) (odds ratio (OR) of 1.29 (95% CI: 1.05, 1.59; p = 0.015) per 1 µg/m³ increase in BC). BC exposure during the second trimester (OR of 1.79 (95% CI: 1.03, 3.09) and PM 2.5 during pregnancy (OR of 1.06 (95% CI: 1.01,1.12) were associated with Low Birth Weight (LBW). Associations with BC remained after adjustment for PM 2.5 . Our study contributes to further evidence of birth weight impact from BC exposure to an emerging pollutant of concern, even in a low-exposure environment. Further, we demonstrate effects of PM 2.5 , but also differentiate independent effects of these two correlated pollutants.

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