Table 3

Early life characteristics and subsequent asthma risk after age 5 years

CharacteristicAsthma n (%)No asthma n (%)Unadjusted HR (95% CI)p ValueAdjusted* HR (95% CI)p Value
Respiratory infection in first year
 Yes7585 (17.9)34 749 (82.1)1.45 (1.41 to 1.49)<0.0011.51 (1.47 to 1.54)<0.001
 No26 819 (12.7)184 775 (87.3)ReferenceReference
Maternal asthma
 Current921 (26.5)2554 (73.5)3.86 (3.61 to 4.12)<0.0011.94 (1.82 to 2.08)<0.001
 Previous222 (23.1)737 (76.9)3.05 (2.67 to 3.48)<0.0011.38 (1.21 to 1.58)<0.001
 None33 261 (13.3)216 233 (86.7)ReferenceReference
Maternal age at delivery (years)
 13–18517 (14.1)3155 (85.9)0.96 (0.88 to 1.05)0.3720.98 (0.90 to 1.07)0.625
 19–2511 451 (14.2)69 383 (85.8)1.02 (1.00 to 1.05)0.0691.03 (1.00 to 1.06)0.026
 26–3012 249 (13.3)79 815 (86.7)ReferenceReference
 31–357276 (13.2)47 971 (86.8)0.99 (0.96 to 1.02)0.4901.02 (0.99 to 1.05)0.140
 36–402562 (13.2)16 868 (86.8)1.00 (0.96 to 1.05)0.8301.05 (1.01 to 1.10)0.029
 41–54349 (13.0)2332 (87.0)1.00 (0.90 to 1.12)0.9341.05 (0.94 to 1.17)0.391
Maternal smoking
 Non-smoker21 701 (13.7)136 972 (86.3)ReferenceReference
 Smoker8278 (14.0)50 968 (86.0)0.93 (0.91 to 0.96)<0.0011.01 (0.99 to 1.04)0.380
 Not recorded4425 (12.3)31 584 (87.7)0.59 (0.57 to 0.61)<0.0010.90 (0.87 to 0.93)<0.001
Child's sex
 Female18 150 (15.0)102 476 (85.0)1.25 (1.22 to 1.27)<0.0011.27 (1.24 to 1.29)<0.001
 Male16 254 (12.2)117 048 (87.8)ReferenceReference
Parity
 114 371 (14.4)85 618 (85.6)ReferenceReference
 212 230 (13.3)79 551 (86.7)0.93 (0.90 to 0.95)<0.0010.90 (0.88 to 0.93)<0.001
 35437 (12.6)37 713 (87.4)0.87 (0.84 to 0.89)<0.0010.84 (0.82 to 0.87)<0.001
 4 or more2366 (12.4)16 642 (87.6)0.88 (0.84 to 0.92)<0.0010.81 (0.78 to 0.85)<0.001
Chronic lung disease
 No34 360 (13.5)219 328 (86.5)ReferenceReference
 Yes44 (18.3)196 (81.7)1.59 (1.18 to 2.14)0.0021.44 (1.06 to 1.96)0.019
  • *Adjusted for child's sex, maternal asthma, maternal age at delivery, year of birth, maternal smoking, gestational age, infection during first year of life, parity and chronic lung disease.