Table 2

Characteristics of children

n=4231
Sex, female51.2 (2166)
Gestational age at birth, weeks*40.1 (37.1–42.1)
Birth weight (g)3450 (545)
Ethnicity, non-European29.1 (1233)
Ever breastfeeding, yes90.9 (3847)
Day care attendance first year, yes57.4 (2428)
FEV1, L2.02 (0.30)
FVC, L2.33 (0.36)
FEV1/FVC, %86.72 (5.66)
FEF75, L/s1.15 (0.35)
FEV1, z-score0.17 (0.97)
FVC, z-score0.21 (0.93)
FEV1/FVC, z-score−0.10 (0.94)
FEF75, z-score0.04 (0.91)
Current asthma, yes5.9 (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.