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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 5.

Odds ratios and 95% confidence intervals (CI) for preterm birth comparing highest quartileb to lower 3 quartiles of traffic density for births in four counties in San Joaquin Valley, 2000–2006 (N=247,487).

Gestational age in weeks N Unadjusted pooled Adjusted pooled Low neighborhood SES Non-lowneighborhood SES
OR 95% CIs aOR 95% CIs N aOR 95% CIs N aOR 95% CIs
37–42 219,237 1.00 – – 1.00 – – 38,131 1.00 – – 181,106 1.00 – –
34–36   20,427 1.10 1.06 1.13 1.04 1.00 1.07    1638 1.04 0.97 1.11   16,222 1.03 0.99 1.07
32–33      3599 1.19 1.11 1.29 1.10 1.01 1.19      865 1.04 0.90 1.21      2734 1.09 1.00 1.20
28–31      2657 1.21 1.11 1.31 1.05 0.95 1.15      268 1.22 1.02 1.46      2021 0.97 0.86 1.09
24–27      1129 1.25 1.10 1.42 1.13 0.96 1.33      276 1.31 0.98 1.75        853 1.03 0.84 1.25
20–23        135 1.35 1.10 1.66 1.25 1.00 1.56      118 1.09 0.73 1.61        320 1.29 0.98 1.69

Abbreviations: aOR, adjusted odds ratio; CI, confidence interval

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: 13,561 vehicles per day