Table 1

Background characteristics related to asthma in a Swedish cohort of 2 775 430 individuals

No asthmaAsthma
n (%)2 514 108 (90.6)261 322 (9.4)
Study individuals’ characteristics
Sex
 Male1 277 846 (50.9)147 383 (56.4)
 Female1 236 255 (49.2)113 939 (43.6)
Prematurity
 Yes (≤37 weeks)144 043 (5.7)22 243 (8.5)
 No (>37 weeks)2 382 811 (94.3)239 079 (91.5)
Small for gestational age
 Yes56 886 (2.2)7145 (2.7)
 No2 382 811 (94.8)245 453 (94.0)
 Missing74 411 (3.0)8724 (3.3)
Life-limiting condition
 Yes28 798 (1.1)6480 (2.5)
 No2 485 310 (98.9)254 842 (97.5)
Family characteristics
Maternal age at delivery, years
 <2052 249 (2.1)5444 (2.1)
 ≥20 to <25420 197 (16.7)45 615 (17.4)
 ≥25 to <30840 276 (33.4)90 611 (34.6)
 ≥30 to <35779 249 (31.0)79 073 (30.3)
 ≥35 to <40349 137 (13.8)33 960 (13.0)
 ≥4071 630 (2.9)6486 (2.5)
 Missing1370 (0.1)133 (0.1)
Maternal smoking during pregnancy
 Yes356 193 (14.2)39 347 (15.1)
 No2 016 479 (80.2)206 644 (79.1)
 Missing141 436 (5.6)15 331 (5.8)
Maternal country of birth
 Sweden2 066 737 (82.2)225 482 (86.3)
 Denmark, Norway, Finland, Iceland69 516 (2.8)6600 (2.5)
 Other374 597 (14.9)29 214 (11.2)
 Missing3258 (0.1)26 (<0.1)
Parental income
 Lowest486 986 (19.4)46 634 (17.9)
 Lower middle481 091 (19.1)51 179 (19.6)
 Middle480 864 (19.1)51 918 (19.9)
 Upper middle480 520 (19.1)51 276 (19.6)
 Highest483 183 (19.2)48 684 (18.6)
 Missing101 464 (4.0)11 631 (4.5)
Parental education
 Compulsory school161 801 (6.4)15 364 (5.9)
 High school1 132 088 (45.1)125 046 (47.8)
 College or further education1 101 778 (43.8)108 189 (41.4)
 Missing118 441 (4.7)12 723 (4.9)
  • The table compares those who received a diagnosis of asthma during follow-up with those who did not receive a diagnosis of asthma during follow-up.