Association between exposure to fine particulate matter and adverse pregnancy outcomes in Kaunas

Abstract

Introduction: Epidemiological studies have suggested that maternal exposure to particulate matter during pregnancy may be associated with adverse health outcomes including low birth weight. However, the findings from these studies have been inconsistent. We examined the effect of long-term exposure to PM2.5 on birth weight by using a linear spline function. Methods: The prospective cohort study included 3292 pregnant women living in Kaunas city, Lithuania between 2007 and 2008. The primary outcomes of the study were low birth weight (LBW < 2500 g) and term low birth weight (TLBW < 2500 g; ≥ 37 weeks gestation). The annual average concentration of PM2.5 at the participants’ home addresses was estimated using land use regression (LUR) model which was developed from the data from air pollution measurements and geographic information systems (GIS). To detect potential confounding variables odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. We used a two-piece linear spline function and multivariate logistic regression analysis to evaluate the association between exposure to PM2.5 and the risk of LBW and TLBW controlling for confounding variables effect. Results: The study results showed that the risk of LBW and TLBW increased statistically significantly with increasing exposure to PM2.5. After adjustment for confounding variables the ORs for LBW among women exposed to the third and fourth quartiles of PM2.5 exposure were 1.27 (95 % CI 0.84–1.93) and 1.69 (95 % CI 1.14–2.50), compared with PM2.5 concentrations below the median. The risk for TLBW among women exposed to the third and fourth quartiles of PM2.5 exposure were 1.78 (95 % CI 0.85–3.73) and 2.89 (95 % CI 1.50–5.60), compared with PM2.5 concentrations below the median. Conclusions: Our study provided evidence that maternal exposure to PM2.5 may adversely affect the birth weight; a non-linear association between exposure to PM2.5 and LBW and TLBW was detected.