Table 3.
Crude and adjusted odds ratios of PM2.5 and preterm birth
| Month of pregnancy | Crude model,* OR (95% CI) | Partial model,† OR (95% CI) | Full model,‡ OR (95% CI) |
|---|---|---|---|
| Month 1§ | |||
| Q2 | 0.69 (0.24, 1.70) | 0.67 (0.23, 1.81) | 0.68 (0.22, 1.65) |
| Q3 | 1.15 (0.49, 2.31) | 1.09 (0.41, 2.27) | 1.13 (0.46, 2.32) |
| Q4 | 1.02 (0.54, 1.80) | 0.95 (0.48, 1.75) | 0.95 (0.51, 1.72) |
| Continuous∥ | 0.93 (0.76, 1.15) | 0.96 (0.77, 1.18) | 0.96 (0.77, 1.19) |
| Month 2§ | |||
| Q2 | 1.16 (0.44, 2.46) | 1.14 (0.53, 2.22) | 1.11 (0.44, 2.80) |
| Q3 | 1.09 (0.42, 2.47) | 1.08 (0.40, 2.60) | 1.06 (0.34, 2.44) |
| Q4 | 1.13 (0.62, 2.10) | 1.09 (0.56, 1.84) | 1.11 (0.57, 2.10) |
| Continuous∥ | 0.99 (0.82, 1.2) | 1.03 (0.85, 1.26) | 1.03 (0.84, 1.25) |
| Month 3§ | |||
| Q2 | 0.98 (0.38, 2.22) | 0.96 (0.32, 2.10) | 1.00 (0.35, 2.18) |
| Q3 | 1.19 (0.44, 2.72) | 1.11 (0.40, 2.44) | 1.14 (0.44, 2.59) |
| Q4 | 1.50 (0.83, 2.56) | 1.47 (0.80, 2.66) | 1.49 (0.82, 2.68) |
| Continuous∥ | 1.09 (0.91, 1.31) | 1.14 (0.94, 1.36) | 1.15 (0.95, 1.38) |
| Month 4§ | |||
| Q2 | 1.34 (0.60, 2.71) | 1.29 (0.55, 2.89) | 1.31 (0.56, 2.91) |
| Q3 | 1.62 (0.69, 3.35) | 1.56 (0.58, 3.25) | 1.62 (0.70, 3.32) |
| Q4 | 1.35 (0.67, 2.43) | 1.30 (0.70, 2.33) | 1.32 (0.69, 2.25) |
| Continuous∥ | 1.04 (0.87, 1.25) | 1.05 (0.87, 1.26) | 1.06 (0.87, 1.27) |
| Month 5§ | |||
| Q2 | 0.96 (0.42, 1.96) | 0.95 (0.41, 1.99) | 0.95 (0.32, 2.38) |
| Q3 | 0.77 (0.26, 1.67) | 0.73 (0.24, 1.88) | 0.71 (0.23, 1.76) |
| Q4 | 1.13 (0.56, 1.96) | 1.13 (0.60, 1.99) | 1.12 (0.60, 1.87) |
| Continuous∥ | 1.08 (0.90, 1.29) | 1.07 (0.88, 1.28) | 1.07 (0.89, 1.29) |
| Month 6§ | |||
| Q2 | 1.12 (0.46, 2.37) | 1.16 (0.44, 2.42) | 1.13 (0.49, 2.37) |
| Q3 | 0.88 (0.33, 2.17) | 0.82 (0.27, 2.23) | 0.81 (0.28, 1.78) |
| Q4 | 1.09 (0.55, 2.09) | 1.11 (0.59, 1.92) | 1.07 (0.57, 1.89) |
| Continuous∥ | 1.05 (0.88, 1.26) | 1.01 (0.85, 1.23) | 0.99 (0.83, 1.20) |
| Month 7§ | |||
| Q2 | 0.80 (0.33, 1.80) | 0.83 (0.28, 1.80) | 0.82 (0.25, 1.82) |
| Q3 | 1.01 (0.40, 2.30) | 1.03 (0.39, 2.14) | 0.99 (0.41, 2.29) |
| Q4 | 1.02 (0.55, 1.80) | 1.10 (0.59, 1.93) | 1.07 (0.57, 1.91) |
| Continuous∥ | 1.06 (0.87, 1.27) | 1.02 (0.83, 1.23) | 1.02 (0.83, 1.22) |
CI = credible interval.
*
Crude model: PM2.5.
†
Partial model: PM2.5, adjusted for temperature.
‡
Full model: PM2.5, adjusted for temperature, maternal age at delivery, household income, maternal education, maternal birthplace, maternal race, maternal smoking status, parity.
§
In all models that look at categorical levels of exposure, Q1 is the referent group.
∥
Continuous results are presented per 10 μg/m3 unit increase.