Respiratory infection in the first year of life and subsequent asthma risk after age 10 years and after age 16 years, stratified by gestational age
| Asthma n (%) | No asthma n (%) | HR (95% CI) | p Value | HR* (95% CI) | p Value | |
|---|---|---|---|---|---|---|
| Asthma ≥age 10 years | ||||||
| Gestational age (weeks) | ||||||
| ≤27 | ||||||
| Infection | 45 (17.9) | 207 (82.1) | 1.83 (1.30 to 2.57) | 0.001 | 1.99 (1.40 to 2.82) | <0.001 |
| No infection | 123 (10.1) | 1098 (89.9) | Reference | Reference | ||
| 28–31 | ||||||
| Infection | 116 (16.0) | 607 (84.0) | 1.43 (1.17 to 1.76) | 0.001 | 1.52 (1.24 to 1.87) | <0.001 |
| No infection | 411 (11.5) | 3167 (88.5) | Reference | Reference | ||
| 32–36 | ||||||
| Infection | 635 (16.3) | 3271 (83.7) | 1.39 (1.27 to 1.52) | <0.001 | 1.46 (1.33 to 1.59) | <0.001 |
| No infection | 2328 (11.9) | 17 200 (88.1) | Reference | Reference | ||
| 37–41 | ||||||
| Infection | 5541 (15.9) | 29 298 (84.1) | 1.44 (1.40 to 1.48) | <0.001 | 1.49 (1.45 to 1.54) | <0.001 |
| No infection | 19 637 (11.3) | 154 557 (88.7) | Reference | Reference | ||
| >41 | ||||||
| Infection | 397 (15.8) | 2110 (84.2) | 1.51 (1.35 to 1.69) | <0.001 | 1.57 (1.41 to 1.76) | <0.001 |
| No infection | 1340 (10.7) | 11 195 (89.3) | Reference | Reference | ||
| Uncertain | ||||||
| Infection | 19 (17.8) | 88 (82.2) | 1.93 (1.14 to 3.28) | 0.015 | 2.05 (1.19 to 3.55) | 0.010 |
| No infection | 50 (9.3) | 488 (90.7) | Reference | Reference | ||
| Asthma ≥age 16 years | ||||||
| Gestational age (weeks) | ||||||
| ≤27 | ||||||
| Infection | 22 (8.8) | 227 (91.2) | 1.56 (0.96 to 2.52) | 0.068 | 1.65 (1.01 to 2.71) | 0.047 |
| No infection | 69 (5.7) | 1132 (94.3) | Reference | Reference | ||
| 28–31 | ||||||
| Infection | 65 (9.2) | 638 (90.8) | 1.41 (1.07 to 1.86) | 0.014 | 1.45 (1.10 to 1.91) | 0.009 |
| No infection | 233 (6.7) | 3249 (93.3) | Reference | Reference | ||
| 32–36 | ||||||
| Infection | 396 (10.5) | 3362 (89.5) | 1.43 (1.28 to 1.60) | <0.001 | 1.49 (1.34 to 1.68) | <0.001 |
| No infection | 1410 (7.5) | 17 379 (92.5) | Reference | Reference | ||
| 37–41 | ||||||
| Infection | 3227 (9.7) | 30 040 (90.3) | 1.37 (1.32 to 1.42) | <0.001 | 1.42 (1.37 to 1.48) | <0.001 |
| No infection | 11 987 (7.2) | 154 347 (92.8) | Reference | Reference | ||
| >41 | ||||||
| Infection | 248 (10.3) | 2161 (89.7) | 1.58 (1.37 to 1.82) | <0.001 | 1.64 (1.42 to 1.90) | <0.001 |
| No infection | 801 (6.7) | 11 244 (93.3) | Reference | Reference | ||
| Uncertain | ||||||
| Infection | 16 (15.2) | 89 (84.8) | 2.48 (1.37 to 4.51) | 0.003 | 2.72 (1.47 to 5.04) | 0.002 |
| No infection | 33 (6.2) | 496 (93.8) | Reference | Reference | ||
*Adjusted for child's sex, maternal asthma, maternal age at delivery, year of birth, maternal smoking, birth weight, infection during first year of life, parity and chronic lung disease.