Table 2 provides the distribution of average PM10 exposures during the different time windows. Average PM10 was close to31 mg/m3 for all windows. Trimester exposures were highly cor-related with entire pregnancy exposure (linear correlation coeffi- cient (r) 4 0.8) and moderately correlated with each other (r be- tween 0.5 and 0.7) (Table3).Correlations between time windows around conception and late pregnancy periods were low (r o 0.4).