Table 2.
Characteristics of children
| n=4231 | |
| Sex, female | 51.2 (2166) |
| Gestational age at birth, weeks* | 40.1 (37.1–42.1) |
| Birth weight (g) | 3450 (545) |
| Ethnicity, non-European | 29.1 (1233) |
| Ever breastfeeding, yes | 90.9 (3847) |
| Day care attendance first year, yes | 57.4 (2428) |
| FEV1, L | 2.02 (0.30) |
| FVC, L | 2.33 (0.36) |
| FEV1/FVC, % | 86.72 (5.66) |
| FEF75, L/s | 1.15 (0.35) |
| FEV1, z-score | 0.17 (0.97) |
| FVC, z-score | 0.21 (0.93) |
| FEV1/FVC, z-score | −0.10 (0.94) |
| FEF75, z-score | 0.04 (0.91) |
| Current asthma, yes | 5.9 (213) |
Lung function measures (n=474) and current asthma (n=591) were missing and not imputed.
Values are mean (SD),
*medians (5%–95% range) or valid percentages (absolute numbers).
FEF75, forced expiratory flow after exhaling 75% of FVC; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.