with 20 mg/m3. Dadvand et al. (2013) combined effect estimates of14 study centers established all over the world and observed a significant decrease in birth weight of 8.9 g (95% CI: 4.6, 13.2 g) for each 10 mg/m3 increase in entire pregnancy exposure to PM10. However, a pooled analysis of data from 14 population-based mother–child cohorts in 12 European countries (Pedersen et al.,2013) showed no significant association between PM10 exposure and birth weight (for an increase of 10 mg/m3: 8 g, 95% CI: 19,3 g).