Low-level nitrogen dioxide exposure and low birth weight risk in Kaunas city

Abstract

Background and Objective. Recent epidemiological studies, conducted in various countries, have reported different level relationships between elevate levels of traffic-related air pollutants and birth outcomes. We studied long-term maternal exposure to NO2 effect on low birth weight (<2500 g, LBW) risk in a Kaunas pregnant women cohort. Methods. This epidemiological study comprised all singleton newborns (2744) born in 2008. We used Kaunas HiWATE cohort data base to obtain information on maternal characteristics and birth outcomes. The following information was available: residential history, socioeconomic characteristics, maternal smoking, family status, education and other. To estimate residential exposure levels to NO2 a database on Kaunas vehicle stock and streets network was developed and measurements of cumulative traffic density were linked to the individual address of the mother. We used an air quality modelling system AIRVIRO and verified exposure modelling results by NO2 level measurements from three air monitoring stations. Results. Basing on modelling results, three NO2 exposure zones where estimated: 1st - referent, mean NO2 level was ≤10 g/m3, 2nd - moderate - NO2 level was 10-20 μg/m3 and 3rd - high - NO2 >21μg/m3. The relationship between NO2 levels and LBW risk was estimated by multivariate logistic regression. After adjustment for gestational age, smoking, family status and education, in moderate exposure zone adjusted odds ratio for LBW was 1.28; 95% CI 0.35-4.64 and in high exposure zone it was 2.48; 95% CI 0.68-9.11. Conclusion. The present study suggests that there might be a relationship between prenatal exposure to relatively low-levels of NO2 and the risk of LBW.