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. 2016 Jan 15;15:6. doi: 10.1186/s12940-016-0094-3

Table 3.

Preterm birth rate by PM2.5 levels in Ohio 2007 – 2010 and trimester of exposure in pregnancy

PM2.5 < 15 μg/m3 PM2.5 ≥ 15 μg/m3
n % Preterm n % Preterm p-value
First trimester 175,649 8.34 49,272 8.87 <0.001
Second trimester 185,883 8.47 39,038 8.43 0.835
Third trimester 181,665 8.08 43,256 10.05 <0.001
Entire pregnancy 200,259 8.27 24,662 9.99 <0.001

% preterm represents the rate of birth <37 weeks of gestational age among the study cohort of singleton non-anomalous live births