Table 1:
Comparison of population characteristics of participants in the whole cohort and those with DNA-m at age 18 years
| Whole cohort (n = 1313) | Sample with DNA-m (n = 369) | P-value | |
|---|---|---|---|
| n (%) | n (%) | ||
| Gender | <0.0001 | ||
| Female | 660 (50.27) | 245 (66.4) | |
| Male | 653 (49.73) | 124 (33.6) | |
| Maternal smoking status | 0.24 | ||
| No | 1002 (76.31 | 292 (79.1) | |
| Yes | 305 (23.23) | 75 (20.3) | |
| Unanswered | 6 (0.46) | 2 (0.5) | |
| Frequency of heavy vehicles passing by home | 0.783 | ||
| >10 per hour | 274 (20.87) | 77 (20.9) | |
| 1–9 per hour | 223 (16.98) | 69 (18.7) | |
| 10 per day | 119 ( 9.06) | 36 (9.8) | |
| Seldom | 427 (32.52) | 120 (32.5) | |
| Never | 241 (18.35) | 67 (18.2) | |
| Missing | 29 (2.21) | ||
| Exposure to smoking outside home | 0.41 | ||
| Yes | 598 (45.54) | 180 (48.8) | |
| No | 663 (50.50) | 181 (49.1) | |
| Unanswered | 52 (3.96) | 8 (2.2) | |
| Current smoking status | 0.3 | ||
| No | 910 (69.31) | 270 (73.2) | |
| Yes | 368 (28.03) | 95 (25.8) | |
| Unanswered | 35 (2.67) | 4 (1.1) | |
| Any exposure to environmental tobacco smoke (at 10 years) | 0.23 | ||
| No | 716 (54.5) | 223 ( 60.4) | |
| Yes | 492 (37.5) | 132 (35.8) | |
| Unanswered | 105 (8.0) | 14 (3.8) | |
| Any exposure to environmental tobacco smoke (at birth, 1 year, 2 year or 4 years) | 0.11 | ||
| No | 602 (45.8) | 186 (50.4) | |
| Yes | 708 (53.9) | 182 (49.3) | |
| Unanswered | 3 (0.23) | 1 (0.27) | |
| Socio-economic status | 0.73 | ||
| High | 103 (7.84) | 33 ( 8.9) | |
| Mid | 952 (72.51) | 267 (72.4) | |
| Low | 177 (13.48) | 58 (15.7) | |
| Unanswered | 81 (6.17) | 11 (2.9) | |
| Living with parents | 0.11 | ||
| Yes | 1158 (88.19) | 342 (92.7) | |
| No | 129 (9.82) | 27 (7.3) | |
| Missing | 26 (1.98) | ||
| Type of residential property | 0.78 | ||
| Rented privately | 145 (11.0) | 28 (7.5) | |
| Rented council/housing association | 209 (15.9) | 65 (17.6) | |
| Owned privately | 908 (69.1) | 271 (73.4) | |
| Other | 18 (1.37) | 5 (1.4) | |
| Missing | 33 (2.51) | ||
| Median (p5, p95) | |||
| BMI | 22.1 (18.2, 32.1) | 22.5 (18.7, 32.1) | 0.09 |
| Age subject started smoking | 15 (12, 17) | 15 (12, 17) | 0.88 |
| Time living in present house | 48 (6, 48) | 48 (6, 48) | 0.48 |
Percentage has been rounded up to whole numbers, where applicable.