Table 4.
Associations between air pollutant PM10 and risk of preterm by exposure window
| PM10 (µg/m3) (U.S. NAAQS level) |
Controls | Preterm | Moderate preterm | Very preterm | Medically indicated preterm |
Spontaneous preterm | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Cases | ORa(95%CI) | Cases | ORa(95%CI) | Cases | ORa(95%CI) | Cases | ORa(95%CI) | Cases | ORa(95%CI) | ||
| Entire pregnancy | |||||||||||
| <150 | 5687 | 419 | 1 | 355 | 1 | 64 | 1 | 111 | 1 | 308 | 1 |
| ≥150 | 2605 | 258 | 1.48(1.22–1.81) | 216 | 1.48(1.20–1.84) | 42 | 1.45(0.91–2.33) | 74 | 1.80(1.24–2.62) | 184 | 1.37(1.09–1.72) |
| 1st trimester | |||||||||||
| <150 | 4591 | 353 | 1 | 295 | 1 | 58 | 1 | 97 | 1 | 256 | 1 |
| ≥150 | 3701 | 324 | 1.17(0.86–1.60) | 276 | 1.30(0.92–1.83) | 48 | 0.71(0.35–1.44) | 88 | 1.06(0.59–1.88) | 236 | 1.25(0.87–1.79) |
| 2nd trimester | |||||||||||
| <150 | 4102 | 343 | 1 | 289 | 1 | 54 | 1 | 93 | 1 | 250 | 1 |
| ≥150 | 4190 | 334 | 0.99(0.75–1.31) | 282 | 1.09(0.80–1.48) | 52 | 0.67(0.35–1.28) | 92 | 1.43(0.84–2.44) | 242 | 0.87(0.64–1.20) |
| 3rd trimester | |||||||||||
| <150 | 4520 | 392 | 1 | 322 | 1 | 70 | 1 | 103 | 1 | 289 | 1 |
| ≥150 | 3772 | 285 | 0.75(0.56–0.99) | 249 | 0.92(0.67–1.26) | 36 | 0.29(0.16–0.52) | 82 | 1.02(0.58–1.79) | 203 | 0.65(0.47–0.90) |
| Last 4 weeks before delivery | |||||||||||
| <150 | 5068 | 400 | 1 | 340 | 1 | 60 | 1 | 111 | 1 | 286 | 1 |
| ≥150 | 3224 | 277 | 1.19(0.94–1.49) | 231 | 1.11(0.86–1.42) | 46 | 1.70(0.96–3.04) | 74 | 1.07(0.69–1.64) | 206 | 1.23(0.94–1.61) |
| Last 6 weeks before delivery | |||||||||||
| <150 | 4916 | 397 | 1 | 340 | 1 | 57 | 1 | 103 | 1 | 294 | 1 |
| ≥150 | 3376 | 280 | 1.08(0.85–1.37) | 231 | 0.96(0.74–1.24) | 49 | 2.03(1.11–3.72) | 82 | 1.40(0.88–2.21) | 198 | 0.99(0.75–1.30) |
| Last 8 weeks before delivery | |||||||||||
| <150 | 4757 | 381 | 1 | 324 | 1 | 57 | 1 | 104 | 1 | 277 | 1 |
| ≥150 | 3535 | 296 | 1.15(0.88–1.48) | 247 | 1.06(0.80–1.40) | 49 | 1.73(0.89–3.33) | 81 | 1.14(0.70–1.87) | 215 | 1.15(0.85–1.55) |
Abbreviations: PM, particulate matter; OR, odds ratio; CI: confident interval
a
Adjusted for maternal age (<25, 25–35, >35 years), parity (primiparous, multiparous), active smoking during pregnancy (yes, no), passive smoking during pregnancy (yes, no), season of conception (fall/winter, summer/spring), prehistory of preterm (yes, no), education level (<college, ≥college), family monthly income per capita (<3000, ≥3000RMB), cooking fuel (gas/electricity, coal/biomass, others), and daily average temperature