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Table 2 Concentration of Exposure to Air Pollutants in the First and Second Trimester of Pregnancy

From: Association of Ambient air Pollution with risk of preeclampsia during pregnancy: a retrospective cohort study

  PE group
(N = 2988)
non-PE group
(N = 113,054)
Z P
PM2.5(μg/m3)
 Trimester 1 72.67 (61.33, 111.67) 71.33 (55.67, 107.67) −6.818 < 0.001
 Trimester 2 70.67 (58.33, 106.67) 68.67 (54.67, 99.67) −7.424 < 0.001
PM10(μg/m3)
 Trimester 1 139.00 (107.67, 181.33) 135.33 (101.00, 169.67) −7.293 < 0.001
 Trimester 2 135.00 (106.67, 169.67) 134.67 (99.00, 160.67) −6.464 < 0.001
NO2 (μg/m3)
 Trimester 1 52.33 (40.00, 63.33) 51.67 (39.67, 63.33) −2.753 0.006
 Trimester 2 50.67 (39.67, 64.00) 50.67 (39.67, 63.33) −3.248 0.001
SO2 (μg/m3)
 Trimester 1 37.33 (23.00, 53.67) 36.67 (23.33, 53.67) −1.344 0.179
 Trimester 2 33.33 (21.67, 50.33) 33.33 (22.00, 49.00) −2.036 0.052
CO (mg/m3)
 Trimester 1 2.23 (1.40, 3.87) 2.37 (1.50, 3.80) −1.300 0.194
 Trimester 2 2.10 (1.40, 3.87) 2.13 (1.40, 3.70) −0.545 0.586
O3 (μg/m3)
 Trimester 1 132.67 (86.00, 174.67) 126.00 (81.67, 170.33) −5.130 < 0.001
 Trimester 2 145.67 (86.00, 182.00) 135.67 (82.67, 180.67) −2.481 0.013
  1. The concentration of exposure to air pollutants were presented as median (interquartile ranges); The difference was analyzed using One-way ANOVA for normally distributed variables and Kruskal-Wallis H test for non-normally distributed variables. Trimester 1 the first trimester of pregnancy, Trimester 2 the second trimester of pregnancy, PE preeclampsia