Table 1.
Association between different stages during or before pregnancy and exposure to six air pollutants
| Air pollutants | Stage | Unadjusted | Adjusted | ||
|---|---|---|---|---|---|
| OR (95% CI) | P value | OR (95% CI) | P value | ||
| PM2.5 | First trimester | 1.038 (1.001, 1.076) | 0.043 | 1.035 (0.999, 1.073) | 0.060 |
| 3 months before pregnancy | 1.018 (0.992, 1.044) | 0.181 | 1.023 (0.995, 1.051) | 0.104 | |
| 6 months before pregnancy | 0.992 (0.969, 1.016) | 0.510 | 0.996 (0.972, 1.021) | 0.758 | |
| 1 year before pregnancy | 1.070 (1.016, 1.127) | 0.010 | 1.080 (1.023, 1.140) | 0.006 | |
| PM10 | First trimester | 1.052 (1.016, 1.089) | 0.004 | 1.051 (1.015, 1.088) | 0.005 |
| 3 months before pregnancy | 1.002 (0.988, 1.016) | 0.805 | 1.005 (0.990, 1.020) | 0.538 | |
| 6 months before pregnancy | 0.993 (0.979, 1.008) | 0.384 | 0.996 (0.981, 1.011) | 0.608 | |
| 1 year before pregnancy | 1.028 (1.001, 1.055) | 0.045 | 1.033 (1.004, 1.062) | 0.024 | |
| CO | First trimester | 1.004 (1.001, 1.006) | 0.003 | 1.003 (1.001, 1.006) | 0.005 |
| 3 months before pregnancy | 1.001 (0.999, 1.002) | 0.390 | 1.001 (0.999, 1.003) | 0.254 | |
| 6 months before pregnancy | 0.999 (0.998, 1.000) | 0.120 | 0.999 (0.998, 1.001) | 0.214 | |
| 1 year before pregnancy | 1.005 (1.001, 1.008) | 0.007 | 1.005 (1.002, 1.009) | 0.005 | |
| NO2 | First trimester | 1.013 (0.970, 1.057) | 0.564 | 1.007 (0.964, 1.052) | 0.759 |
| 3 months before pregnancy | 0.972 (0.926, 1.020) | 0.244 | 0.977 (0.930, 1.026) | 0.353 | |
| 6 months before pregnancy | 0.939 (0.896, 0.984) | 0.009 | 0.943 (0.899, 0.990) | 0.018 | |
| 1 year before pregnancy | 2.231 (1.114, 4.469) | 0.024 | 2.174 (1.085, 4.356) | 0.029 | |
| SO2 | First trimester | 1.134 (1.029, 1.250) | 0.011 | 1.135 (1.029, 1.251) | 0.011 |
| 3 months before pregnancy | 1.017 (0.981, 1.054) | 0.365 | 1.023 (0.985, 1.062) | 0.242 | |
| 6 months before pregnancy | 0.989 (0.954, 1.026) | 0.571 | 0.995 (0.958, 1.034) | 0.814 | |
| 1 year before pregnancy | 1.127 (1.048, 1.213) | 0.001 | 1.137 (1.053, 1.229) | 0.001 | |
| O3 | First trimester | 0.980 (0.969, 0.992) | 0.001 | 0.981 (0.970, 0.993) | 0.002 |
| 3 months before pregnancy | 1.004 (0.990, 1.019) | 0.554 | 1.002 (0.988, 1.017) | 0.761 | |
| 6 months before pregnancy | 1.011 (0.999, 1.023) | 0.084 | 1.009 (0.997, 1.022) | 0.157 | |
| 1 year before pregnancy | 0.991 (0.941, 1.044) | 0.729 | 0.982 (0.929, 1.037) | 0.504 | |