Table 2.
The Summary of Pooled Effect Sizes
| Pollutant | Number of Studies | Pooled OR (95% CI)a | I2 (%) | Pheter | Pegger | Pbegg |
|---|---|---|---|---|---|---|
| Prenatal exposure | ||||||
| PM2.5 | 1 | 2.150 (0.096-42.653) | NA | NA | NA | NA |
| SPM | 1 | 1.130 (0.790-1.610) | NA | NA | NA | NA |
| CO | 1 | 1.001 (1.000-1.001) | NA | NA | NA | NA |
| NO | 1 | 1.024 (1.016-1.032) | NA | NA | NA | NA |
| NO2 | 2 | 2.189 (0.913-5.246) | NA | NA | NA | NA |
| 1.005 (1.005-1.011) | ||||||
| NOx | 1 | 1.005 (1.005-1.010) | NA | NA | NA | NA |
| SO2 | 1 | 1.489 (1.060-2.052) | NA | NA | NA | NA |
| O3 | 1 | 0.995 (0.990-1.000) | NA | NA | NA | NA |
| Short-term postnatal exposure | ||||||
| PM2.5 | 3 | 1.011 (1.003-1.019) | 0 | 0.97 | 0.353 | 0.296 |
| PM10 | 3 | 1.004 (1.000-1.008) | 38 | 0.20 | 0.203 | 1.000 |
| CO | 2 | 1.000 (0.998-1.003) | NA | NA | NA | NA |
| 1.000 (1.000-1.001) | ||||||
| NO | 1 | 1.472 (1.004-2.155) | NA | NA | NA | NA |
| NO2 | 4 | 1.003 (0.997-1.008) | 46 | 0.14 | 0.701 | 1.000 |
| SO2 | 4 | 1.038 (0.942-1.144) | 58 | 0.07 | 0.213 | 0.308 |
| O3 | 3 | 1.017 (0.965-1.071) | 85 | <0.01 | 0.094 | 1.000 |
| Long-term postnatal exposure | ||||||
| PM2.5 | 3 | 1.415 (1.179-1.697) | 41 | 0.19 | 0.296 | 0.083 |
| SPM | 1 | 1.110 (0.730-1.680) | NA | NA | NA | NA |
| CO | 1 | 1.000 (1.000-1.001) | NA | NA | NA | NA |
| NO | 2 | 1.016 (1.008-1.024) | NA | NA | NA | NA |
| 0.922 (0.781-1.084) | ||||||
| NO2 | 2 | 1.005 (1.000-1.011) | NA | NA | NA | NA |
| 1.054 (0.948-1.170) | ||||||
| NOx | 1 | 1.005 (1.000-1.005) | NA | NA | NA | NA |
| SO2 | 1 | 1.000 (0.856-1.161) | NA | NA | NA | NA |
| O3 | 1 | 1.000 (0.995-1.005) | NA | NA | NA | NA |
CO = carbon monoxide; NA = not applicable; NO = nitric oxide; NO2 = nitrogen dioxide; NOx = nitrogen oxides; O3 = ozone; Pbegg = significance of the Beggs test; Pegger = significance of the Egger's test; Pheter = significance of the heterogeneity test; PM = particulate matter; SO2 = sulfur dioxide; SPM = suspended particulate matter.
a
The pooled OR (95% CI) was calculated by meta-analysis (number of studies ≥3) or presented by the OR (95% CI) of each study (number of studies <3).