Associations between PM2.5 and NO2 exposure in different pregnancy periods and adverse birth outcomes (adjusted models)
| Per IQR increase in | Mean difference | ORs | |||||
| Birth weight, g (95% CI) | Birth length, cm (95% CI) | PTB (case: 33) (95% CI) | LBW (case: 30) (95% CI) | LGA (case: 108) (95% CI) | SGA (case: 84) (95% CI) | ||
| (N=941) | (N=927) | (N=945) | (N=945) | (N=945) | (N=945) | ||
| Estimated exposure to PM2.5 | 90 days prior to conception | 59.73 (−16.52 to 135.98) | 0.15 (−0.176 to 0.48) | 0.24 (0.06 to 1.00) | 0.49 (0.18 to 1.29) | 1.40 (0.72 to 2.71) | 1.66 (0.75 to 3.68) |
| First trimester | 6.21 (−73.79 to 86.20) | 0.04 (−0.308 to 0.388) | 0.88 (0.28 to 2.80) | 0.76 (0.21 to 2.81) | 0.86 (0.45 to 1.67) | 1.33 (0.58 to 3.04) | |
| Second trimester | −37.64 (−107.73 to 32.44) | 0.02 (−0.283 to 0.326) | 1.62 (0.53 to 4.96) | 1.34 (0.38 to 4.68) | 1.00 (0.55 to 1.83) | 0.94 (0.50 to 1.76) | |
| Third trimester | 4.20 (−73.17 to 81.57) | −0.17 (−0.509 to 0.162) | 0.92 (0.29 to 2.90) | 0.92 (0.30 to 2.85) | 1.29 (0.65 to 2.53) | 0.83 (0.42 to 1.66) | |
| Total pregnancy | 8.01 (−41.10 to 57.11) | 0.02 (−0.198 to 0.230) | 0.77 (0.38 to 1.54) | 0.62 (0.31 to 1.25) | 1.15 (0.75 to 1.77) | 0.84 (0.52 to 1.35) | |
| Estimated exposure to NO2 | 90 days prior to conception | −1.03 (−41.88 to 39.81) | −0.04 (−0.215 to 0.139) | 0.84 (0.45 to 1.57) | 1.04 (0.54 to 1.98) | 1.31 (0.91 to 1.88) | 1.45 (0.99 to 2.12) |
| First trimester | −9.78 (−50.84 to 31.28) | 0.04 (−0.133 to 0.223) | 0.90 (0.49 to 1.65) | 1.03 (0.56 to 1.91) | 1.21 (0.85 to 1.72) | 1.57 (1.06 to 2.32) | |
| Second trimester | −20.82 (−59.11 to 17.47) | −0.06 (−0.222 to 0.112) | 1.31 (0.73 to 2.34) | 1.34 (0.75 to 2.40) | 1.21 (0.86 to 1.70) | 1.36 (0.95 to 1.95) | |
| Third trimester | −9.50 (−56.00 to 36.99) | −0.01 (−0.213 to 0.191) | 0.79 (0.40 to 1.59) | 0.95 (0.47 to 1.94) | 1.42 (0.94 to 2.13) | 1.51 (0.97 to 2.36) | |
| Total pregnancy | −8.45 (−37.73 to 20.83) | 0.00 (−0.125 to 0.130) | 0.97 (0.62 to 1.51) | 1.04 (0.66 to 1.64) | 1.20 (0.93 to 1.56) | 1.33 (1.01 to 1.75) | |
All significant findings in the table are bold.
Models adjusted for maternal age at enrolment, infant’s sex, maternal body mass index at 11–14 weeks’ gestation, primiparity, monthly household income level and season of births.
LBW, low birth weight; LGA, large for gestational age; NO2, nitrogen dioxide ; PM2.5, particulate matter with diameter ≤2.5; PTB, pre-term birth ; SGA, small for gestational age.