Table 4.
Hazard ratios for an IQR increase from Cox proportional hazards modelsa on cause-specific infant mortality for normal-birth-weight infants in a birth cohort, Seoul, Korea, 2004–2007.
| Exposure | Hazard ratio (95% CI)
|
|
|---|---|---|
| Respiratory | SIDS | |
| Gestational exposure
| ||
| TSP (IQR, 8.91 μg/m3) | ||
| All | 3.78 (1.18–12.13) | 0.92 (0.33–2.58) |
| First trimester | 2.08 (1.26–3.43) | 1.02 (0.72–1.45) |
| Second trimester | 0.96 (0.64–1.45) | 0.80 (0.58–1.10) |
| Third trimester | 1.03 (0.71–1.48) | 1.00 (0.74–1.37) |
| PM10 (IQR, 6.93 μg/m3) | ||
| All | 6.20 (1.50–25.66) | 1.15 (0.38–3.48) |
| First trimester | 2.19 (1.30–3.70) | 1.04 (0.70–1.55) |
| Second trimester | 0.97 (0.59–1.60) | 0.79 (0.53–1.17) |
| Third trimester | 1.04 (0.66–1.64) | 0.95 (0.64–1.41) |
| PM2.5 (IQR, 3.15 μg/m3) | ||
| All | 3.15 (1.26–7.85) | 1.42 (0.71–2.87) |
| First trimester | 1.58 (1.14–2.19) | 1.14 (0.82–1.59) |
| Second trimester | 1.09 (0.61–1.93) | 0.89 (0.54–1.47) |
| Third trimester | 1.46 (0.79–2.68) | 0.80 (0.48–1.35) |
| PM10–2.5 (IQR, 3.71 μg/m3) | ||
| All | 2.86 (0.76–10.85) | 0.57 (0.16–1.96) |
| First trimester | 1.45 (0.99–2.14) | 0.95 (0.69–1.31) |
| Second trimester | 0.94 (0.63–1.39) | 0.81 (0.60–1.10) |
| Third trimester | 0.93 (0.66–1.32) | 1.01 (0.76–1.34) |
| Lifetime exposure
| ||
| TSP (IQR, 18.99 μg/m3) | 0.35 (0.07–1.86) | 0.81 (0.33–2.00) |
| PM10 (IQR, 3.48 μg/m3) | 0.65 (0.43–0.99) | 0.73 (0.57–0.94) |
| PM2.5 (IQR, 1.25 μg/m3) | 0.63 (0.42–0.95) | 0.88 (0.71–1.09) |
| PM10–2.5 (IQR, 2.01 μg/m3) | 0.70 (0.48–1.01) | 0.66 (0.51–0.86) |
The 352,405 infants of normal birth weight in this analysis include 22 respiratory deaths and 26 SIDS deaths.
a
The model included the following variables: sex, gestation period, educational level of mother, maternal age, season of birth, and heat index.