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Table 1 Description of the main cohort, n = 7898

From: Asthma incidence in children growing up close to traffic: a registry-based birth cohort

   N (%) HR (95% CI)a
1st purchase, inhaled β2-agonist
Sex Girl 3784 (49) 1.0
Boy 3996 (51) 1.3 (1.2–1.5)
Missing 118  
Birth weight 2500–4000 (normal) 6079 (78) 1.0
500–2499 (low) 301 (4) 1.1 (0.9–1.5)
4001–6500 (high) 1396 (18) 1.1 (1.0–1.3)
Missing 122  
Smoking during pregnancy No 7275 (94) 1.0
Yes 499 (6) 1.2 (1.0–1.5)
Missing 124  
Environmental tobacco smoke No 6591 (85) 1.0
Yes 1177 (15) 1.2 (1.1–1.4)
Missing 130  
Breastfeeding ≥8 months 3920 (56) 1.0
<8 months 2807 (40) 1.2 (1.1–1.3)
Never breastfed 278 (4) 1.3 (1.0–1.6)
Missing 893  
Parental allergy No 3177 (46) 1.0
Yes 3751 (54) 1.2 (1.1–1.4)
Missing 970  
Furred pets at home No 5790 (75) 1.0
Yes 1922 (25) 1.0 (0.9–1.1)
Missing 186  
Mold at home No 7326 (95) 1.0
Yes 386 (5) 1.0 (0.8–1.3)
Missing 186  
Problems to pay bills Never or seldom 7361 (96) 1.0
Yes, >6 months/year 348 (5) 0.8 (0.6–1.0)
Missing 189  
Swedish parents Yes, both Swedish 4811 (62) 1.0
One foreign 1290 (17) 0.9 (0.8–1.1)
Both foreign 1689 (22) 0.8 (0.7–1.0)
Missing 108  
Highest education any parent >12 years 5612 (73) 1.0
9–12 years 1792 (23) 1.1 (1.0–1.3)
≤ 9 years 297 (4) 1.1 (0.8–1.4)
Missing 197  
Type of housing Owned house 2783 (36) 1.0
Tenant-owned apartment 2242 (29) 0.9 (0.8–1.0)
Rented apartment 2616 (34) 0.9 (0.8–1.1)
Other 101 (1) 0.7 (0.4–1.1)
Missing 156  
City Vellinge 449 (6) 1.0
Svedala 664 (8) 0.9 (0.7–1.2)
Trelleborg 611 (8) 1.1 (0.8–1.4)
Malmö 6134 (78) 0.8 (0.6–1.0)
Missing 40  
Birth year 2005 1066 (14) 1.0
2006 2395 (30) 1.1 (0.9–1.3)
2007 1664 (21) 1.0 (0.8–1.2)
2008 2179 (28) 1.0 (0.9–1.2)
  2009 594 (8) 1.2 (0.9–1.5)
  1. aUnadjusted.