Table 2 Baseline characteristics by secondhand smoke exposure from the SCHEDULE study in China
Secondhand smoke exposure/daily, %a | ||||||
|---|---|---|---|---|---|---|
Characteristics | None | < 1 h | 1–2 h | ≥3 h | p value | |
| Â | N (%) | 20.8 | 63.1 | 10.5 | 5.6 | Â |
Sex | 0.968 | |||||
 Boys | 9242 (53.8) | 53.8 | 53.4 | 53.6 | 54.0 |  |
 Girls | 7943 (46.2) | 46.2 | 46.6 | 46.4 | 46.0 |  |
Age (Mean score) | Â | 9.1 | 9.2 | 9.2 | 9.2 | 0.55 |
Household income | < 0.001 | |||||
 ≤30,000 | 1564 (13.1) | 9.1 | 13.4 | 16.1 | 13.3 |  |
 30,000-100,000 | 5306 (44.5) | 35.2 | 46.6 | 48.4 | 44.7 |  |
 100,000-300,000 | 4190 (35.1) | 42 | 34.3 | 30.6 | 35.2 |  |
 ≥300,000 | 864 (7.3) | 13.7 | 5.7 | 4.9 | 6.8 |  |
Maternal education | < 0.001 | |||||
 Middle school or below | 5594 (34.0) | 24.9 | 36.3 | 37.1 | 29.3 |  |
 High school | 4386 (26.7) | 22.1 | 27.4 | 30.5 | 30.1 |  |
 College or above | 6467 (39.3) | 53.0 | 36.4 | 32.4 | 40.6 |  |
Paternal education | < 0.001 | |||||
 Middle school or below | 4834 (29.1) | 19.4 | 31.1 | 34.5 | 25.8 |  |
 High school | 5005 (30.2) | 23.3 | 31.8 | 33.7 | 34.1 |  |
 College or above | 6743 (40.7) | 57.3 | 37.1 | 31.8 | 40.1 |  |
Mode of birth | 0.06 | |||||
 Vaginal | 8012 (50.2) | 48.8 | 50.3 | 52.5 | 48.4 |  |
 Cesarean | 7933 (49.8) | 51.2 | 49.7 | 47.5 | 51.6 |  |
Place of birth | < 0.001 | |||||
 Shanghai | 8096 (52.2) | 48.8 | 52.9 | 55.0 | 57.4 |  |
 Others | 7402 (47.8) | 51.2 | 47.1 | 45.0 | 42.6 |  |
BMI z-score (Mean score) | Â | 0.21 | 0.30 | 0.30 | 0.38 | 0.01 |