Table 1.
Characteristics of the children with pulmonary function data (years 1995, 1996, and 1997) at ages 8, 9, and 10 years
| Characteristic | Age 8 (1995) (n = 328) |
Age 9 (1996) (n = 299) |
Age 10 (1997) (n = 344) |
|---|---|---|---|
| Age (years), mean (SD) | 8.2 (0.5) | 9.3 (0.4) | 10.3 (0.5) |
| Female, n (%) | 143 (44) | 126 (42) | 153 (45) |
| Height (cm), mean (SD) | 133 (6) | 138 (6) | 143 (7) |
| Weight (kg), mean (SD) | 30 (6) | 33 (7) | 39 (9) |
| FEV1 (L), mean (SD) | 1.8 (0.3) | 1.9 (0.3) | 2.1 (0.3) |
| FVC (L), mean (SD) | 2.1 (0.3) | 2.3 (0.3) | 2.5 (0.4) |
| FEV1/FVC (%), mean (SD) | 88 (6) | 84 (6) | 85 (5) |
| DDE (μg/L), median (IQR) | 0.3 (0.2) | 0.4 (0.2) * | 0.3 (0.2) |
| Doctor diagnosed asthma, n (%) | 42 (13) | 36 (12) | 46 (13) |
| Maternal asthma, n (%) | 12 (4) | 11 (4) | 12 (4) |
| Paternal asthma, n (%) | 18 (6) | 17 (6) | 18 (5) |
| Breast feeding, n (%) | 281 (86) | 257 (86) | 293 (85) |
| Maternal smoking during pregnancy (per day), n (%) | |||
| >30 cigarettes | 3 (1) | 3 (1) | 4 (1) |
| 20–30 cigarettes | 3 (1) | 3 (1) | 4 (1) |
| 11–20 cigarettes | 13 (4) | 10 (3) | 14 (4) |
| 1–-10 cigarettes | 74 (23) | 66 (22) | 78 (13) |
| Environmental tobacco smoke (per day), n (%) | |||
| >30 cigarettes | 2 (1) | 2 (1) | 5 (2) |
| 20–30 cigarettes | 5 (2) | 4 (1) | 5(2) |
| 11–20 cigarettes | 19 (6) | 16 (5) | 21 (6) |
| 1–-10 cigarettes | 82 (25) | 71 (24) | 79 (23) |
* DDE values at 9 years of age were carried forward from 8 years of age. The different median resulted from a different number of participants at 8 and 9 years of age.