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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Environ Res. 2014 Aug 28;134:198–204. doi: 10.1016/j.envres.2014.08.002

Table 3.

Unadjusted and adjusted odds ratio for the association of air pollutants and adverse birth outcomes for every interquartile (IQR)a increase in exposure.

Exposure period Term LBW PTD VPTD
Unadjusted Adjustedb Unadjusted Adjustedc Unadjusted Adjustedc
O3 (ppb)
Trimester 1 1.002 (0.976,1.029) 0.994 (0.967,1.023) 1.026 (1.012,1.039)* 1.012 (0.998,1.027) 1.022 (0.988,1.057) 1.054 (1.016, 1.093)*
Trimester 2 0.980 (0.954,1.007) 0.978 (0.950,1.007) 1.026 (1.012,1.040)* 1.023 (1.008,1.039)* 1.014 (0.980,1.050) 1.072 (1.033, 1.113)*
Trimester 3 0.954 (0.928,0.980)* 0.940 (0.912,0.969)* 1.003 (0.989,1.017) 0.993 (0.978,1.008) 0.963 (0.924,1.004) 0.984 (0.940, 1.030)
Pregnancy 0.959 (0.926,0.994)* 0.938 (0.900,0.977)* 1.039 (1.020,1.058)* 1.028 (1.007, 1.050)* 1.018 (0.973,1.066) 1.125 (1.067, 1.186)*
PM2.5 (μg/m3)
Trimester 1 1.037 (1.011,1.064)* 1.007 (0.981, 1.034) 1.046 (1.032,1.059)* 1.029 (1.016, 1.043)* 1.090 (1.055,1.126)* 1.063 (1.028, 1.098)*
Trimester 2 1.059 (1.032,1.087)* 1.034 (1.007, 1.061)* 1.139 (1.124,1.154)* 1.123 (1.109, 1.138)* 1.252 (1.214,1.291)* 1.215 (1.177, 1.253)*
Trimester 3 1.035 (1.010,1.061)* 1.005 (0.980, 1.031) 1.039 (1.026,1.052)* 1.026 (1.012, 1.039)* 1.038 (1.000,1.078) 1.010 (0.972, 1.049)
Pregnancy 1.050 (1.024,1.076)* 1.015 (0.989, 1.041) 1.071 (1.057,1.084)* 1.053 (1.040, 1.067)* 1.116 (1.082,1.151)* 1.082 (1.048, 1.117)*
a

Interquartile range for O3 in ppb: 7.8 for trimester 1, 8.0 for trimester 2, 8.0 for trimester 3, 7.1 for the entire pregnancy; for PM2.5 in μg/m3: 2.6 for trimester 1, 2.6 for trimester 2, 2.8 for trimester 3, and 2.0 for the entire pregnancy.

b

Adjusted for maternal education, ethnicity, marital status, maternal age, infant gender, prenatal care status, alcohol, smoking, season of conception, census group income, urbanicity, presence or absence of maternal risk factor, infection, PTD status, or co-morbidity.

c

Adjusted for maternal education, ethnicity, marital status, age, infant gender, prenatal care status, alcohol, smoking, census group income, urbanicity, presence or absence of maternal risk factor, LBW status, or co-morbidity.

*

Indicates statistical significance at p<0.05