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. Author manuscript; available in PMC: 2015 Dec 1.
Published in final edited form as: Ann Epidemiol. 2014 Dec;24(12):888–95e4. doi: 10.1016/j.annepidem.2014.10.004

Table 4.

Adjusted oddsa ratios (aOR) and 95% confidence intervals (CI) for preterm birth comparing highest quartileb to lower 3 quartiles of each pollutant exposure among those with low neighborhood socioeconomic status in four counties in San Joaquin Valley, 2000–2006 (N=44,231).

Exposure Gestational age in weeks N Entire Pregnancy First Trimester Second Trimester Third Trimester
aOR 95% CI aOR 95% CI aOR 95% CI aOR 95% CI
CO 37–42 35,295 1.00 – – 1.00 – – 1.00 – – 1.00 – –
34–36   3912 1.11 1.03 1.20 0.98 0.92 1.06 1.09 1.01 1.17 0.95 0.88 1.02
32–33    808 1.06 0.90 1.25 0.86 0.74 1.01 1.00 0.86 1.17 1.05 0.89 1.22
28–31    573 0.90 0.73 1.11 0.79 0.65 0.96 1.25 1.04 1.51 1.02 0.83 1.25
24–27    266 0.71 0.50 1.01 0.52 0.37 0.74 2.73 2.02 3.68 NC – –
20–23    113 0.58 0.35 0.95 0.55 0.35 0.87 2.38 1.60 3.54 NC – –
NO2 37–42 37,815 1.00 – – 1.00 – – 1.00 – – 1.00 – –
34–36    4178 1.06 0.99 1.13 0.98 0.92 1.05 1.07 1.00 1.15 1.00 0.94 1.07
32–33      859 1.10 0.95 1.28 0.94 0.82 1.09 1.06 0.92 1.22 1.12 0.97 1.29
28–31      633 0.89 0.74 1.08 1.00 0.84 1.20 1.11 0.93 1.33 1.05 0.88 1.27
24–27      274 0.98 0.72 1.32 0.60 0.44 0.81 2.14 1.58 2.90 NC – –
20–23      115 0.77 0.51 1.17 0.42 0.27 0.66 3.67 2.28 5.91 NC – –
PM10 37–42 37,811 1.00 – – 1.00 – – 1.00 – – 1.00 – –
34–36    4170 1.13 1.05 1.21 1.08 1.00 1.16 1.13 1.06 1.22 0.99 0.92 1.06
32–33      843 1.21 1.03 1.41 1.25 1.07 1.45 1.24 1.06 1.44 0.97 0.84 1.14
28–31      586 0.98 0.80 1.21 1.06 0.87 1.29 1.23 1.02 1.50 0.63 0.50 0.78
24–27      274 2.64 1.95 3.56 1.22 0.90 1.66 2.49 1.86 3.34 NC – –
20–23      114 2.37 1.59 3.52 1.18 0.78 1.77 3.98 2.66 5.98 NC – –
PM2.5 37–42 37,740 1.00 – – 1.00 – – 1.00 – – 1.00 – –
34–36    4168 1.24 1.15 1.33 0.99 0.92 1.06 1.13 1.05 1.21 0.97 0.90 1.04
32–33      854 1.58 1.36 1.84 0.93 0.80 1.08 1.25 1.08 1.45 1.09 0.93 1.26
28–31      623 1.59 1.31 1.92 0.85 0.70 1.03 1.82 1.52 2.19 1.63 1.35 1.97
24–27      274 2.36 1.75 3.18 0.46 0.33 0.66 3.14 2.33 4.24 NC – –
20–23      115 0.69 0.42 1.11 0.50 0.31 0.79 4.30 2.85 6.48 NC – –

Abbreviations: OR, odds ratio; CI, confidence interval; NC, not calculated

a

Adjusted for maternal age, education, race, infant birth weight, prenatal care initiation in first trimester, Medi-Cal payment of birth costs

b

Cut-offs for highest quartile of exposure: CO 0.60 ppm; NO2 19.49 ppb; PM10 42.77 μg/m3; PM2.5 20.75 μg/m3