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. Author manuscript; available in PMC: 2015 Aug 18.
Published in final edited form as: Environ Res. 2013 Mar 21;123:9–16. doi: 10.1016/j.envres.2013.01.006

Table 4.

Associations between Trimester Specific Air Pollution Exposure and Hypertensive Disorder of Pregnancy, Stratified by BMI Categories

Pollutant Trimester Non-Obese (BMI <30kg/m2) Obese (BMI ≥30kg/m2) Pinteraction
Case/control OR (95% CI)* Case/control OR (95% CI)*
CO (ppm) 1st 94/119 4.68 (1.69, 12.99) 38/30 0.81 (0.21, 3.10) 0.02
2nd 94/119 0.71 (0.27, 1.83) 38/30 1.28 (0.34, 4.78) 0.79
3rd 94/119 0.84 (0.37, 1.87) 38/30 1.85 (0.45, 7.60) 0.06
NO2 (ppb) 1st 94/119 2.05 (0.94, 4.48) 38/30 0.51 (0.11, 2.40) 0.04
2nd 94/119 0.52 (0.24, 1.16) 38/30 0.94 (0.27, 3.31) 0.32
3rd 94/119 0.92 (0.46, 1.88) 38/30 0.84 (0.24, 3.00) 0.25
O3 (ppb) 1st 94/119 0.68 (0.36, 1.29) 38/30 1.42 (0.44, 4.57) 0.17
2nd 94/119 2.16 (1.12, 4.17) 38/30 1.36 (0.43, 4.26) 0.34
3rd 94/119 1.44 (0.77, 2.70) 38/30 1.03 (0.37, 2.91) 0.04
PM2.5 (µg/m3) 1st 94/119 8.63 (3.10, 24.14) 38/30 0.72 (0.14, 3.56) 0.06
2nd 94/119 1.74 (0.75, 4.01) 38/30 2.41 (0.66, 8.76) 0.51
3rd 94/119 1.28 (0.59, 2.78) 38/30 1.39 (0.34, 5.60) 0.23
PM10 (µg/m3) 1st 94/119 0.75 (0.36, 1.55) 38/30 0.89 (0.26, 3.09) 0.97
2nd 94/119 0.63 (0.31, 1.28) 38/30 0.75 (0.28, 2.00) 0.64
3rd 94/119 1.99 (0.90, 4.41) 38/30 0.68 (0.22, 2.04) 0.09
*

The odds ratios (ORs) and 95% confidence intervals (CIs) are reported per 2 standard deviations (2SD) increase in the pollutant concentration. The 2SDs for CO, NO2, O3, PM2.5, and PM10 were 1ppm, 14 ppb, 15 ppb, 7µg/m3 and 13µg/m3, respectively.

All models are adjusted for maternal age (continuous), parity, maternal smoking history, exposure to secondhand smoke during pregnancy, and year of conception (before or after 2002).

P values for interaction are obtained using the likelihood ratio test.

Subjects with missing BMI (N=17) were not included in this analysis (N=281).