Prevalence and unadjusted ORs for adolescents' wheeze (self-reported) at age 15 years in relation to demographic, adolescent, and parental factors
| Population distribution (%) | Ever wheeze | Current wheeze | |||
| % | OR (95% CI) | % | OR (95% CI) | ||
| Background and demographics | |||||
| Gender (n=9065) | |||||
| Girls (reference) | 48.5 | 22.0 | 12.2 | ||
| Boys | 51.5 | 18.7 | 0.81 (0.72 to 0.91)* | 8.9 | 0.70 (0.60 to 0.82)* |
| Birth weight, g (n=9066) | |||||
| <2500 | 3.2 | 22.6 | 1.11 (0.80 to 1.55) | 12.0 | 1.13 (0.74 to 1.73) |
| 2500–2999 | 8.7 | 19.4 | 0.92 (0.73 to 1.15) | 11.4 | 1.07 (0.81 to 1.42) |
| 3000–3499 | 31.0 | 19.5 | 0.92 (0.79 to 1.06) | 9.7 | 0.89 (0.73 to 1.07) |
| 3500–3999 (reference) | 37.2 | 20.8 | 10.8 | ||
| 4000–4499 | 16.4 | 20.5 | 0.98 (0.83 to 1.17) | 11.2 | 1.04 (0.83 to 1.31) |
| ≥4500 | 3.5 | 24.3 | 1.22 (0.89 to 1.67) | 11.5 | 1.08 (0.71 to 1.64) |
| Socioeconomic status at birth (n=8017) | |||||
| I. Professional/entrepreneur | 17.8 | 20.8 | 1.03 (0.87 to 1.23) | 10.2 | 0.96 (0.76 to 1.21) |
| II. Skilled non-manual | 15.5 | 17.4 | 0.82 (0.68 to 1.00)* | 7.9 | 0.72 (0.56 to 0.94)* |
| III. Skilled manual (reference) | 40.9 | 20.4 | 10.5 | ||
| IV. Unskilled/apprentice | 5.5 | 25.0 | 1.30 (0.98 to 1.73) | 13.2 | 1.29 (0.90 to 1.85) |
| Farmer | 9.0 | 19.3 | 0.94 (0.74 to 1.18) | 10.7 | 1.02 (0.75 to 1.37) |
| Other: (student/at home/sick pension/unemployed) | 11.3 | 22.4 | 1.13 (0.92 to 1.39) | 12.8 | 1.25 (0.96 to 1.63) |
| Marital status at birth (n=9037) | |||||
| Married (reference) | 80.5 | 19.9 | 10.3 | ||
| Cohabitation | 14.3 | 21.5 | 1.10 (0.93 to 1.31) | 11.1 | 1.08 (0.86 to 1.36) |
| Single | 4.2 | 28.5 | 1.60 (1.21 to 2.13)* | 16.3 | 1.69 (1.19 to 2.39)* |
| Divorced/widow | 0.9 | 24.1 | 1.28 (0.68 to 2.39) | 7.4 | 0.70 (0.25 to 1.93) |
| Maternal education at child's birth (n=7839) | |||||
| Primary school (reference) | 26.6 | 20.9 | 10.2 | ||
| Vocational school | 44.7 | 20.5 | 0.98 (0.83 to 1.14) | 10.6 | 1.05 (0.85 to 1.29) |
| Matriculation | 20.9 | 19.8 | 0.94 (0.78 to 1.13) | 10.0 | 0.98 (0.76 to 1.25) |
| University | 7.8 | 16.7 | 0.76 (0.58 to 0.99)* | 8.4 | 0.81 (0.57 to 1.16) |
| Family history of atopy | |||||
| Maternal asthma (n=6225) | |||||
| No (reference) | 92.6 | 18.9 | 9.8 | ||
| Yes | 7.4 | 36.4 | 2.45 (1.99 to 3.03)* | 18.3 | 2.06 (1.58 to 2.68)* |
| Paternal asthma (n=6181) | |||||
| No (reference) | 93.6 | 19.4 | 9.9 | ||
| Yes | 6.4 | 34.3 | 2.17 (1.73 to 2.73)* | 19.7 | 2.23 (1.69 to 2.94)* |
| Maternal allergy/eczema (n=6264) | |||||
| No (reference) | 69.7 | 17.8 | 9.3 | ||
| Yes | 30.3 | 26.4 | 1.66 (1.45 to 1.90)* | 13.2 | 1.49 (1.25 to 1.77)* |
| Paternal allergy/eczema (n=6155) | |||||
| No (reference) | 80.0 | 19.1 | 10.0 | ||
| Yes | 20.0 | 24.8 | 1.40 (1.20 to 1.63)* | 12.4 | 1.27 (1.04 to 1.56)* |
| Exposure to smoking | |||||
| Parents smoking during gestation (n=8126) | |||||
| Neither parent (reference) | 52.4 | 18.6 | 9.0 | ||
| One parent | 31.0 | 21.5 | 1.20 (1.05 to 1.37)* | 11.9 | 1.37 (1.14 to 1.64)* |
| Both parents | 11.7 | 23.8 | 1.36 (1.13 to 1.65)* | 13.0 | 1.51 (1.18 to 1.94)* |
| Adolescents current smoking, at age 15 years (n=4615) | |||||
| No (reference) | 49.1 | 17.0 | 7.7 | ||
| Occasionally | 21.0 | 24.1 | 1.55 (1.29 to 1.87)* | 12.3 | 1.69 (1.32 to 2.16)* |
| Once/week or more | 29.9 | 31.9 | 2.29 (1.95 to 2.68)* | 21.1 | 3.21 (2.62 to 3.93)* |
| Maternal and adolescent weight | |||||
| Pre-pregnancy weight (n=8874) | |||||
| First tertile 35–54 (reference)† | 32.3 | 19.1 | 9.1 | ||
| Second tertile 55–61 | 33.0 | 19.9 | 1.05 (0.91 to 1.22) | 10.5 | 1.17 (0.96 to 1.43) |
| Third tertile 62–130 | 34.7 | 22.1 | 1.20 (1.04 to 1.39)* | 12.0 | 1.35 (1.11 to 1.64)* |
| Continuous predictor (% per kg) | 0.7% (0.1% to 1.3%) p=0.023* | 1.0% (0.3% to 1.8%) p=0.009* | |||
| Pre-pregnancy BMI (n=8838) | |||||
| <19 (underweight) | 7.4 | 19.8 | 0.91 (0.72 to 1.16) | 10.1 | 1.07 (0.79 to 1.45) |
| 19–24.9 (normal) (reference) | 75.3 | 18.4 | 10.7 | ||
| 25–29.9 (overweight) | 13.3 | 24.5 | 1.31 (1.10 to 1.55)* | 12.0 | 1.22 (0.97 to 1.53) |
| ≥30 (obese) | 3.8 | 20.9 | 1.07 (0.78 to 1.48) | 14.5 | 1.52 (1.04 to 2.21)* |
| Continuous predictor \(% per BMI unit) | 2.7% (0.9% to 4.4%) p=0.002* | 3.5% (1.3% to 5.8%) p=0.002* | |||
| Adolescent BMI at age 15 yrs (n=6669) | |||||
| Continuous predictor (% per BMI unit) | 4.8% (2.9% to 6.6%) p<0.0005* | 4.8% (2.4% to 7.1%) p<0.0005* | |||