The possible association between exposure to air pollution and the risk for congenital malformations.

Abstract Background Over the last decade, there is growing evidence that exposure to air pollution may be associated with increased risk for congenital malformations. Objectives To evaluate the possible association between exposures to air pollution during pregnancy and congenital malformations among infants born following spontaneously conceived (SC) pregnancies and assisted reproductive technology (ART) pregnancies. Methods This is an historical cohort study comprising 216,730 infants: 207,825 SC infants and 8905 ART conceived infants, during the periods 1997–2004. Air pollution data including sulfur dioxide (SO 2 ), particulate matter 10 ), nitrogen oxides (NO x ) and ozone (O 3 ) were obtained from air monitoring stations database for the study period. Using a geographic information system (GIS) and the Kriging procedure, exposure to air pollution during the first trimester and the entire pregnancy was assessed for each woman according to her residential location. Logistic regression models with generalized estimating equation (GEE) approach were used to evaluate the adjusted risk for congenital malformations. Results In the study cohort increased concentrations of PM 10 and NO x pollutants in the entire pregnancy were associated with slightly increased risk for congenital malformations: OR 1.06(95% CI, 1.01–1.11) for 10 µg/m 3 increase in PM 10 and OR 1.03(95% CI, 1.01–1.04) for 10 ppb increase in NO x . Specific malformations were evident in the circulatory system (for PM 10 and NO x exposure) and genital organs (for NO x exposure). SO 2 and O 3 pollutants were not significantly associated with increased risk for congenital malformations. In the ART group higher concentrations of SO 2 and O 3 in entire pregnancy were associated (although not significantly) with an increased risk for congenital malformations: OR 1.06(95% CI, 0.96–1.17) for 1 ppb increase in SO 2 and OR 1.15(95% CI, 0.69–1.91) for 10 ppb increase in O 3. Conclusions Exposure to higher levels of PM 10 and NO x during pregnancy was associated with an increased risk for congenital malformations. Specific malformations were evident in the circulatory system and genital organs. Among ART pregnancies possible adverse association of SO 2 and O 3 exposure was also observed. Further studies are warranted, including more accurate exposure assessment and a larger sample size for ART pregnancies, in order to confirm these findings.