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) |