Total N=1899 n (%)
Outcome variables  
RI in the last 12 months 691 (36.4%)
Wheezing ever 538 (28.3%)
Recent Wheeze 247 (13.0%)
Asthma diagnosis 131 (12.2%)a
Predictors  
SHS exposureb:  
No 1403 (73.9%)
In utero (maternal) 50 (2.6%)
Current 298 (15.7%)
Both in utero and current 91 (4.8%)
THS exposureb,c:  
No 1251 (83.4%)
Yes (≥1 per week) 78 (5.2%)
Potential confounders  
Age  
< 6 years 821 (43.2%)
≥ 6 years 1073 (56.5%)
Genderb  
Male gender 1018 (53.6%)
Female 871(45.9%)
Gestational ageb  
<37 weeks 114 (6.0%)
≥37 weeks 1736 (91.4%)
Complications during pregnancy / birth  
No 1616 (85.1%)
Yes 283 (14.9%)
Birth weightb  
Low birth weight (<2500g) 100 (5.3%)
Normal birth weight (≥2500g) 1701 (89.6%)
Breastfeedingb  
No breastfeeding 670 (35.3%)
<6 months 688 (36.2%)
6 – 12 months 413 (21.7%)
> 12 months 108 (5.7%)
Atopic first degree relative  
No 587 (30.9%)
Yes 1312 (69.1%)
Child at high risk of asthmab  
No 1141 (60.1%)
Yes 473 (24.9%)
Vitamin D use:  
Never 1209 (63.7%)
Sometimes 167 (8.8%)
Daily 523 (27.5)
  Total N=1899 n (%)
Potential confounders cont.  
≥1 siblings  
No 530 (27.9%)
Yes 1368 (72.0%)
Day care attendance  
No 285 (15.0%)
Yes   1614 (85.0%)
Highest parental education  
Low 72 (3.8%)
Middle 530 (27.9%)
High 858 (45.2%)
Academic 425 (22.4%)
achildren <6 years, asthma diagnosis not applicable.
bvalues may not add up to 100% because of missing values.
cn=389 children with current SHS exposure excluded
Table 1: Characteristics of the study population.
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