Table 1.
Characteristics for the birth cohort in Seoul, Korea, 2004–2007.
| Characteristic | Eligible births (n = 359,459)
|
Total mortality (all causes; n = 225) | |
|---|---|---|---|
| Normal birth weight (n = 352,405) | Low birth weight (n = 7,054) | ||
| Sex (%) | |||
| Male | 51.6 | 40.8 | 52.0 |
| Female | 48.4 | 59.2 | 48.0 |
| Age at death [years (mean ± SD)] | — | — | 0.40 ± 0.25 |
| Birth weight [kg (mean ± SD)] | 3.31 ± 0.38 | 2.30 ± 0.18 | 3.13 ± 0.49 |
| Gestational age [weeks (mean ± SD)] | 39.3 ± 1.1 | 38.1 ± 1.1 | 39.0 ± 1.1 |
| 37–38 weeks (%) | 25.2 | 67.5 | 38.7 |
| 39–40 weeks (%) | 63.4 | 30.5 | 54.7 |
| 41–42 weeks (%) | 11.3 | 2.0 | 6.6 |
| 43–44 weeks (%) | 0.1 | 0.0 | 0.00 |
| Mother’s age (%) | |||
| < 20 years | 0.2 | 0.4 | 1.3 |
| 20–24 years | 4.3 | 4.4 | 5.3 |
| 25–29 years | 36.3 | 32.5 | 34.2 |
| 30–34 years | 46.7 | 47.0 | 45.8 |
| 35–39 years | 11.2 | 13.8 | 12.0 |
| > 39 years | 1.3 | 1.9 | 1.3 |
| Educational level of mother [years (%)] | |||
| ≤ 6 | 0.3 | 0.5 | 0.4 |
| 7–12 | 33.2 | 35.4 | 39.6 |
| > 12 | 66.5 | 64.1 | 60.0 |
| Season of birth (%) | |||
| Winter | 25.1 | 24.2 | 26.2 |
| Spring | 25.7 | 25.9 | 26.7 |
| Summer | 23.7 | 24.1 | 27.6 |
| Fall | 25.5 | 25.8 | 19.5 |
| Pollution exposures during pregnancy [μg/m3 (mean ± SD)] | |||
| TSP | |||
| Gestation | 96.7 ± 6.6 | 96.3 ± 7.2 | 98.0 ± 6.5 |
| First trimester | 94.8 ± 18.6 | 94.1 ± 18.6 | 94.9 ± 18.3 |
| Second trimester | 93.1 ± 18.2 | 93.3 ± 18.3 | 95.3 ± 17.5 |
| Third trimester | 93.1 ± 20.1 | 92.8 ± 21.0 | 98.3 ± 19.2 |
| PM10 | |||
| Gestation | 61.3 ± 4.2 | 61.2 ± 4.6 | 62.2 ± 4.4 |
| First trimester | 61.7 ± 12.0 | 61.4 ± 12.0 | 61.1 ± 11.8 |
| Second trimester | 60.5 ± 11.7 | 60.6 ± 11.8 | 61.0 ± 11.0 |
| Third trimester | 60.7 ± 12.7 | 60.6 ± 13.4 | 62.9 ± 12.0 |
| PM2.5 | |||
| Gestation | 30.6 ± 2.3 | 30.5 ± 2.3 | 31.5 ± 2.5 |
| First trimester | 31.1 ± 5.1 | 30.9 ± 4.9 | 31.7 ± 5.8 |
| Second trimester | 30.1 ± 4.1 | 30.1 ± 4.1 | 30.5 ± 4.0 |
| Third trimester | 30.2 ± 4.6 | 30.1 ± 4.9 | 31.1 ± 4.5 |
| PM10–2.5 | |||
| Gestation | 30.6 ± 2.6 | 30.6 ± 2.9 | 30.7 ± 2.7 |
| First trimester | 30.6 ± 8.1 | 30.4 ± 8.1 | 29.4 ± 7.5 |
| Second trimester | 30.4 ± 8.2 | 30.5 ± 8.2 | 30.5 ± 7.7 |
| Third trimester | 30.5 ± 8.6 | 30.5 ± 9.0 | 31.8 ± 8.2 |
| Lifetime pollution exposure [μg/m3 (mean ± SD)] | |||
| TSP | 88.7 ± 14.4 | 88.8 ± 14.7 | 91.7 ± 18.5 |
| PM10 | 59.5 ± 5.7 | 59.5 ± 6.0 | 59.1 ± 11.6 |
| PM2.5 | 29.1 ± 1.7 | 29.1 ± 1.9 | 29.5 ± 4.6 |
| PM10–2.5 | 30.5 ± 4.1 | 30.5 ± 4.2 | 29.7 ± 7.5 |