Discussion The aim of our study was to investigate the role of oxidative DNA damage, possibly induced by exposure to air pollution (meas- ured as concentrations of B[a]P and PM2.5) and modulated by genetic polymorphisms in selected relevant genes, in the risk of adverse pregnancy outcomes. Our results indicate that increased 8-oxodG levels in placental DNA are an independent factor associated with the risk of IUGR as well as LBW. The role of air pollution in our samples seems to be minor. Oxidative stress during pregnancy is a normal physiological condition, and the fetus possesses mechanisms that help to minimize the deleterious effects of the production of ROS. These mechanisms include the expres- sion of the antioxidant enzymes catalase, glutathione peroxidase, GST, thiol/disulfide oxidoreductase, and superoxide dismutase, as well as the accumulation of antioxidants (glu- tathione and vitamins C and E) (Myatt and Cui 2004). However, in the case of excessive ROS production, apoptosis in the trophoblast is induced (Smith et al. 1999), which in turn increases the risk of IUGR (Myatt and Cui 2004). Several authors have reported increased levels of various oxidative stress markers dur- ing pregnancy and subsequent unfavorable pregnancy outcomes. The levels of malondi- aldehyde and xanthine oxidase were elevated in maternal and umbilical cord plasma and placental tissues with IUGR when compared with controls (Biri et al. 2007). Elevated uri- nary 8-oxodG levels during early pregnancy were predictors of LBW (Peter Stein et al. 2008; Potdar et al. 2009). Other authors reported associations of increased levels of oxidative stress markers measured in the third trimester of pregnancy with unfavorable preg- nancy outcomes (Orhan et al. 2003; Scholl and Stein 2001). In our study, we measured 8-oxodG levels in placental DNA at delivery, with similar results of elevated oxidative DNA damage in both IUGR and LBW newborns. Apart from endogenous factors, oxida- tive stress may be also affected by various exogenous stimuli, including ambient air pol- lution. Numerous studies have shown that exposure to air pollutants increases the lev- els of oxidative stress markers (Avogbe et al. 2005; reviewed by Kelly 2003; Loft et al. 2008; Rossner et al. 2007, 2008a, 2008b; Sorensen et al. 2003a, 2003b). Pollutants are mostly adsorbed onto PM of various sizes. After entering the organism, PM exerts its negative effect either by means of chemical compounds adsorbed to PM or via inflam- mation-related pathways directly linked with ROS production and thus oxidative stress induction (Risom et al. 2005). In agreement with these observations, we found that 8-ox- odG levels were associated with exposure to PM2.5 during the second month of pregnancy; Factors associated with pregnancy outcomes this association, however, vanished in the final multivariate-adjusted model. No significant associations were detected for B[a]P exposure. The effect of various ambient air pollut- ants on adverse pregnancy outcomes has been analyzed in numerous studies with conflict- ing results. Exposure to PM < 10 µm during the first month of pregnancy was associated with increased risk of IUGR (Dejmek et al. 1999). Similarly, c-PAH exposure during the first gestational month significantly elevated IUGR (Dejmek et al. 2000). LBW and the prevalence of premature births were associated with the concentrations of sulfur dioxide and total suspended particles during individual trimesters of pregnancy: LBW was associated with concentrations of both sulfur dioxide and total suspended particles in all three trimesters, whereas prematurity was associated with sulfur dioxide in three trimesters and with total sus- pended particles only in the first trimester of pregnancy (Bobak 2000). LBW was increased in association with residence within 50 m of highways, but no direct effect of PM2.5 on LBW was found (Brauer et al. 2008). The results from other studies are also discussed in reviews (Maisonet et al. 2004; Sram et al. 2005). In this study, we observed evidence of an effect of air pollution on pregnancy out- comes, specifically the association of PM2.5 concentrations in the first month of pregnancy and LBW. The estimated effect of PM2.5 and B[a]P on IUGR was not significant. We did not observe any influence of B[a]P exposure on LBW. However, a significant association between exposure to PM2.5 and LBW did not remain after adjusting for other variables pos- sibly affecting adverse pregnancy outcomes. Because the samples analyzed in this study partially overlap with the samples described by Dejmek et al. (1999, 2000), it would be reasonable to expect similar results for the Table 5. Results from univariate and multivariate-adjusted logistic regression of factors associated with IUGR. Univariate analysis Multivariate analysis Variable Crude OR (95% CI) p-Valuea ORb (95% CI) p-Valuea 8-OxodG/105 dG (below/above median) 1.47 (1.02–2.12) 0.037 1.57 (1.06–2.34) 0.026 District (Prachatice/Teplice) 1.21 (0.82–1.80) 0.331 0.90 (0.57–1.44) 0.669 Ethnicity (European/Romani) 2.43 (1.59–3.72) < 0.001 1.51 (0.85–2.68) 0.157 Sex (male/female) 1.14 (0.79–1.63) 0.480 1.12 (0.76–1.66) 0.557 Gestational age (below/above median) 0.96 (0.67–1.39) 0.842 1.13 (0.74–1.71) 0.580 Mother’s age at delivery (below/above median) 0.71 (0.50–1.02) 0.067 0.94 (0.64–1.47) 0.891 Mother’s BMI (below/above median) 0.66 (0.46–0.95) 0.025 0.74 (0.50–1.10) 0.137 Mother’s smoking (no/yes) 1.78 (1.24–2.57) 0.002 1.31 (0.84–2.05) 0.234 Mother’s education [years (below/above median)] 0.51 (0.34–0.77) 0.001 0.62 (0.37–1.02) 0.060 Marital status (single/married) 0.65 (0.41–1.02) 0.059 1.12 (0.62–2.02) 0.711 Vitamin intake during pregnancy (times per week; 0.74 (0.51–1.06) 0.103 0.96 (0.64–1.45) 0.847 below/above median) Father’s education [years (below/above median)] 0.53 (0.35– 0.81) 0.003 0.78 (0.47–1.29) 0.336 Father’s smoking (no/yes) 1.40 (0.96–2.06) 0.083 1.05 (0.66–1.66) 0.852 ap-Value estimated using logistic regression analysis. bAdjusted for all the factors in the table. Table 6. Results from univariate and multivariate-adjusted logistic regression of factors associated with LBW. Univariate analysis Multivariate analysis Variable Crude OR (95% CI) p-Valuea ORb (95% CI) p-Valuea 8-OxodG/105 dG (below/above median) 1.36 (0.93–1.98) 0.109 1.83 (1.12–3.00) 0.017 District (Prachatice/Teplice) 3.33 (2.00–5.53) < 0.001 1.77 (0.90–3.45) 0.097 Ethnicity (European/Romani) 3.80 (2.50–5.79) < 0.001 0.86 (0.42–1.74) 0.668 Sex (male/female) 1.48 (1.02–2.16) 0.042 1.96 (1.21–3.18) 0.006 Gestational age (below/above median) 0.05 (0.03–0.10) < 0.001 0.05 (0.03–0.11) < 0.001 Mother’s age at delivery (below/above median) 1.07 (0.74–1.56) 0.721 1.39 (0.83–2.34) 0.214 Mother’s BMI (below/above median) 0.61 (0.42–0.89) 0.011 0.70 (0.42–1.14) 0.149 Mother’s smoking (no/yes) 2.30 (1.56–3.39) < 0.001 1.94 (1.10–3.44) 0.023 Mother’s education [years (below/above median)] 0.75 (0.50–1.12) 0.161 1.46 (0.79–2.69) 0.228 Marital status (single/married) 0.41 (0.27–0.64) < 0.001 0.70 (0.36–1.38) 0.304 Vitamin intake during pregnancy [times per week 0.53 (0.36–0.78) 0.001 0.68 (0.41–1.13) 0.134 (below/above median)] Father’s education [years (below/above median)] 0.52 (0.33–0.81) 0.004 0.78 (0.41–1.46) 0.434 Father’s smoking (no/yes) 1.74 (1.15–2.65) 0.009 0.77 (0.42–1.39) 0.384 PM2.5 levels [first month of pregnancy (below/ 1.90 (1.29–2.81) 0.001 0.89 (0.52–1.54) 0.685 above median)] rs8081047 (CC vs. CT + TT) 2.40 (1.54–3.74) < 0.001 1.46 (0.11–18.6) 0.773 rs16969415 (TT vs. CT + CC) 2.41 (1.54–3.79) < 0.001 0.78 (0.06–10.5) 0.854 rs854477 (GG vs. AG + AA) 0.48 (0.33–0.71) < 0.001 1.31 (0.80–2.15) 0.289 Haplotype in MBL2 (ATAATCCGCT/ ATAATCCGCT 2.11 (1.45–3.08) < 0.001 2.59 (1.59–4.20) < 0.001 vs. other combinations, Table 4) ap-Value estimated using logistic regression analysis. bAdjusted for all the factors in the table. Environmental Health Perspectives • volume 119 | number 2 | February 2011 269