Multiple logistic regression of possible perinatal risk factors for asthma in 16 year old Finnish adolescents. Crude and adjusted odds ratios (OR) with 95% confidence intervals (CI)2-1
| Perinatal risk factors | Proportion in category and total no. | Occurrence of asthma (% and no. affected) | Crude OR | 95% CI | Adjusted OR2-2 | 95% CI | Adjusted OR2-3 | 95% CI |
| Individual birth factors | ||||||||
| Birth weight (g) | ||||||||
| <2000 | 10.5% | 4.4% (21) | 1.0 | 1.0 | 1.0 | |||
| 2000–2499 | 23.6% | 3.6% (38) | 0.82 | 0.45 to 1.50 | 0.78 | 0.40 to 1.51 | 0.73 | 0.36 to 1.90 |
| 2500–2999 | 38.2% | 3.5% (61) | 0.80 | 0.46 to 1.41 | 0.69 | 0.37 to 1.31 | 0.61 | 0.30 to 1.24 |
| ⩾3000 | 27.7% | 4.6% (57) | 1.05 | 0.60 to 1.84 | 1.12 | 0.59 to 2.13 | 0.93 | 0.44 to 1.97 |
| n = 4502 | Test for trend2-4 | p = 0.6 | p = 0.4 | p = 0.8 | ||||
| Ponderal index in quarters | ||||||||
| –23.60 | 25.3% | 3.1% (35) | 1.0 | 1.0 | 1.0 | |||
| 23.61–25.30 | 24.8% | 3.3% (36) | 1.02 | 0.64 to 1.63 | 1.02 | 0.60 to 1.74 | 1.01 | 0.58 to 1.74 |
| 25.31–26.96 | 24.8% | 3.5% (38) | 1.12 | 0.72 to 1.76 | 1.08 | 0.64 to 1.84 | 0.99 | 0.57 to 1.70 |
| 26.97– | 25.2%2-5 | 5.9% (65) | 1.82 | 1.18 to 2.79 | 1.86 | 1.13 to 3.07 | 1.67 | 0.98 to 2.87 |
| n = 4403 | Test for trend | p<0.01 | p<0.01 | p<0.05 | ||||
| Apgar score | ||||||||
| ⩾7 | 89.9% | 3.7% (122) | 1.0 | 1.0 | 1.0 | |||
| <7 | 10.1% | 4.8% (18) | 1.39 | 0.84 to 2.30 | 1.13 | 0.62 to 2.06 | 1.25 | 0.66 to 2.39 |
| n = 3710 | ||||||||
| Neonatal hospitalisation | ||||||||
| No | 70.5% | 3.7% (114) | 1.0 | 1.0 | 1.0 | |||
| Yes | 29.5% | 4.6% (60) | 1.24 | 0.88 to 1.75 | 1.17 | 0.79 to 1.74 | 1.06 | 0.60 to 1.88 |
| n = 4406 | ||||||||
| Birth factors common to both members of the pair | ||||||||
| Gestational age (weeks) | ||||||||
| <33 | 7.1% | 3.9% (11) | 1.0 | 1.0 | ||||
| 33− 36 | 29.0% | 3.7% (42) | 0.94 | 0.43 to 2.04 | 0.88 | 0.39 to 1.99 | ||
| 37−40 | 60.6% | 4.0% (96) | 1.03 | 0.49 to 2.13 | 0.90 | 0.42 to 1.96 | ||
| >40 | 3.3% | 4.6% (6) | 1.19 | 0.37 to 3.83 | 1.43 | 0.46 to 4.42 | ||
| n = 3968 | Test for trend | p = 0.6 | p = 0.8 | |||||
| Maternal age at birth of twins (years) | ||||||||
| <25 | 31.4% | 5.1% (73) | 1.0 | 1.0 | ||||
| 25–30 | 38.8% | 3.5% (62) | 0.67 | 0.46 to 0.99 | 0.71 | 0.45 to 1.11 | ||
| >30 | 29.8% | 3.2% (44) | 0.62 | 0.41 to 0.94 | 0.75 | 0.46 to 1.23 | ||
| n = 4578 | Test for trend | p<0.05 | p = 0.2 | |||||
↵2-1 Regression results corrected by generalised estimating equations (GEE).
↵2-2 OR adjusted for zygosity, birth order (A/B-twin), sex, number of older siblings, parental asthma, and maternal smoking.
↵2-3 Additionally adjusted for the corresponding birth factor of the co-twin.
↵2-4 Wald's statistic for trend in logistic regression.
↵2-5 Percentages add up to 100.1% due to rounding.