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. Author manuscript; available in PMC: 2020 May 18.
Published in final edited form as: Environ Res. 2019 Jan 10;171:218–227. doi: 10.1016/j.envres.2019.01.013

Table 4:

Multivariable Regression Models for Categorical Exposures and Per IQR Increases in Ozone and PM2.5

Exposure categoriesa Cases / Controls Model 1b Model 2c
aOR (95% CI) aOR (95% CI)
PM2.5 1st trimester (μg/m3)
3.9 – <10.1 (referent) 64/932 1.00 1.00
10.1 – <14.9 256/3819 0.98 (0.72, 1.32) 0.93 (0.67, 1.30)
14.9 – 21.8 65/941 1.06 (0.72, 1.56) 0.99 (0.66, 1.51)
Per IQR increase (3.39) -- 1.03 (0.86, 1.23) 1.05 (0.86, 1.28)
PM2.5 2nd trimester (μg/m3)
4.2 – <10.1 (referent) 50/923 1.00 1.00
10.1 – <14.9 269/3810 1.36 (0.98, 1.89) 1.44 (1.01, 2.05)
14.9 – 20.7 66/959 1.30 (0.85, 1.99) 1.41 (0.89, 2.24)
Per IQR increase (3.34) -- 1.08 (0.91, 1.29) 1.13 (0.93, 1.38)
PM2.5 3rd trimester (μg/m3)
3.9 – <9.9 (referent) 62/936 1.00 1.00
9.9 – <15.1 254/3763 0.99 (0.73, 1.35) 0.98 (0.70, 1.37)
15.1 – 24.4 65/951 1.05 (0.70, 1.58) 1.04 (0.67, 1.61)
Per IQR increase (3.72) -- 0.98 (0.81, 1.20) 0.96 (0.77, 1.20)
PM2.5 entire pregnancy (μg/m3)
5.3 – <10.8 64/944 1.00 1.00
10.8 – <14.0 252/3800 0.95 (0.69, 1.30) 0.87 (0.63, 1.21)
14.0 – 18.3 69/948 1.07 (0.75, 1.53) 0.99 (0.67, 1.46)
Per IQR increase (2.02) -- 1.01 (0.98, 1.04) 1.01 (0.97, 1.04)
PM2.5 1st year of life (μg/m3)
5.2 – <11.7 (referent) 44/946 1.00 1.00
11.7 – <13.8 277/3807 1.67 (1.17, 2.38) 1.84 (1.26, 2.69)
13.8 – 17.5 64/939 1.40 (0.94, 2.09) 1.54 (0.98, 2.40)
Per IQR increase (0.90) -- 1.07 (0.98, 1.17) 1.11 (1.00, 1.23)
PM2.5 2nd year of life (μg/m3)
8.7 – <11.5 (referent) 63/991 1.00 1.00
11.5 – <13.2 268/3835 1.10 (0.82, 1.48) 1.10 (0.81, 1.50)
13.2 – 17.4 54/866 0.97 (0.61, 1.55) 1.13 (0.67, 1.94)
Per IQR increase (0.87) -- 0.98 (0.88, 1.09) 1.07 (0.93, 1.23)
PM2.5, CEI (μg/m3)
7.2 – <11.8 (referent) 51/982 1.00 1.00
11.8 – <13.2 267/3798 1.37 (1.00, 1.86) 1.41 (1.02, 1.95)
13.2 – 14.8 67/912 1.45 (0.98, 2.15) 1.52 (1.00, 2.31)
Per IQR increase (0.94) -- 1.10 (0.94, 1.28) 1.17 (0.98, 1.40)
Ozone 1st trimester (ppb)
18.5 – <27.8 (referent) 76/970 1.00 1.00
27.8 – <48.6 259/3825 0.76 (0.52, 1.10) 0.70 (0.47, 1.04)
48.6 – 65.3 50/897 0.59 (0.35, 1.00) 0.56 (0.33, 0.96)
Per IQR increase (15.54) -- 0.87 (0.61, 1.25) 0.87 (0.60, 1.26)
Ozone 2nd trimester (ppb)
18.5 – <28.1 (referent) 70/964 1.00 1.00
28.1 – <49.2 252/3780 0.93 (0.64, 1.36) 0.96 (0.65, 1.42)
49.2 – 65.4 63/948 0.94 (0.57, 1.55) 0.92 (0.54, 1.55)
Per IQR increase (15.66) -- 0.92 (0.62, 1.35) 0.85 (0.56, 1.29)
Ozone 3rd trimester (ppb)
17.5 – <27.6 (referent) 62/935 1.00 1.00
27.6 – <49.7 246/3784 0.94 (0.65, 1.37) 0.92 (0.62, 1.35)
49.7 – 65.2 73/931 1.16 (0.71, 1.88) 1.17 (0.71, 1.93)
Per IQR increase (16.50) -- 1.22 (0.82, 1.80) 1.19 (0.80, 1.77)
Ozone entire pregnancy (ppb)
23.7 – <34.3 (referent) 62/967 1.00 1.00
34.3 – <44.6 259/3784 1.16 (0.83, 1.63) 1.23 (0.86, 1.75)
44.6 – 59.4 64/941 1.18 (0.74, 1.86) 1.28 (0.78, 2.10)
Per IQR increase (7.39) -- 1.00 (0.99, 1.00) 1.00 (0.99, 1.01)
Ozone 1st year of life (ppb)
32.8 – <36.5 (referent) 66/924 1.00 1.00
36.5 – <41.6 251/3818 0.94 (0.70, 1.25) 0.95 (0.69, 1.31)
41.6 – 48.5 68/950 1.04 (0.72, 1.49) 1.19 (0.79, 1.81)
Per IQR increase (3.83) -- 1.05 (0.87, 1.27) 1.22 (0.96, 1.54)
Ozone 2nd year of life (ppb)
32.8 – <36.6 (referent) 49/887 1.00 1.00
36.6 – <41.5 273/3836 1.41 (1.00, 1.99) 1.42 (0.98, 2.05)
41.5 – 45.4 63/969 1.28 (0.84, 1.96) 1.29 (0.81, 2.05)
Per IQR increase (3.66) -- 1.19 (0.95, 1.48) 1.27 (0.96, 1.69)
Ozone CEI (ppb)
33.1 – <37.3 (referent) 67/927 1.00 1.00
37.3 – <41.4 252/3789 0.95 (0.71, 1.28) 1.02 (0.76, 1.37)
41.4 – 45.6 66/976 0.99 (0.66, 1.47) 1.16 (0.76, 1.78)
Per IQR increase (2.79) -- 1.07 (0.88, 1.29) 1.19 (0.95, 1.49)

CEI=Cumulative Exposure Index (pregnancy through 2nd year of life)

a

Sextiles with middle 2–5 categories collapsed into one group.

b

Model 1 adjusted for year of birth, mother’s education, birth spacing, maternal pre-pregnancy body mass index, month of conception.

c

Model 2 adjusted for year of birth, mother’s education, birth spacing, maternal pre-pregnancy body mass index, and month of conception, multi-window (except for CEI models), and multi-pollutant. Multi-window models: 1st trimester models adjusted for 3rd trimester average exposure; 2nd trimester models adjusted for 3rd trimester average exposure; 3rd trimester models adjusted for 1st trimester average exposure; 1st year of life models adjusted for pregnancy average exposure; 2nd year of life models adjusted for pregnancy average exposure. Multi-pollutant models: ozone models adjusted for PM2.5 average exposures for the same time period; PM2.5 models adjusted for ozone average exposure during the same time period.