Adjusted prevalence odds ratios for asthma and atopy outcomes between the categories of birth parameters with the middle category being used as the reference
| No. | Ever asthma OR (95% CI) | Drug therapy OR (95% CI) | Asthma in past 2 years OR (95% CI) | BHR OR (95% CI) | IgE ⩾150 IU* OR (95% CI) | Skin test +ve (weal ⩾2 mm) OR (95% CI) | |
|---|---|---|---|---|---|---|---|
| Birth length (cm) | |||||||
| <50 | 103 | 1.0 (0.3 to 3.3) | 1.4 (0.4 to 4.4) | 1.0 (0.3 to 3.7) | 1.0 (0.3 to 3.4) | 1.0 (0.5 to 2.3) | 0.7 (0.4 to 1.5) |
| 50–55.9 | 597 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| ⩾56 | 34 | 6.4 (2.0 to 19.8) | 4.6 (1.4 to 15.7) | 3.9 (1.1 to 13.4) | 0.8 (0.1 to 6.6) | 0.8 (0.2 to 2.5) | 1.1 (0.4 to 2.7) |
| p value for trend | 734 | 0.05 | 0.11 | 0.04 | 0.56 | 0.42 | 0.75 |
| Head circumference (cm) | |||||||
| <34 | 154 | 1.7 (0.8 to 3.9) | 1.5 (0.7 to 3.5) | 1.4 (0.6 to 3.4) | 1.0 (0.3 to 2.7) | 1.0 (0.5 to 1.9) | 0.5 (0.3 to 1.0) |
| 34–36.9 | 531 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| ⩾37 | 49 | 0.2 (0.1 to 0.9) | 0.4 (0.1 to 1.6) | 0.1 (0.0 to 0.9) | 0.9 (0.2 to 4.3) | 3.4 (1.4 to 7.9) | 1.2 (0.6 to 2.8) |
| p value for trend | 734 | 0.86 | 0.91 | 0.67 | 0.26 | 0.02 | 0.75 |
| Birth weight (kg) | |||||||
| <3.0 | 150 | 0.2 (0.0 to 0.6) | 0.1 (0.0 to 0.5) | 0.2 (0.0 to 0.6) | 0.8 (0.3 to 2.6) | 0.9 (0.4 to 1.9) | 0.9 (0.5 to 1.8) |
| 3.0–3.9 | 501 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| ⩾4.0 | 84 | 1.0 (0.4 to 2.4) | 0.5 (0.2 to 1.4) | 1.2 (0.5 to 3.0) | 0.4 (0.1 to 1.6) | 0.6 (0.3 to 1.2) | 0.6 (0.3 to 1.2) |
| p value for trend | 735 | 0.70 | 0.34 | 0.69 | 0.24 | 0.49 | 0.47 |
| Older siblings | |||||||
| 0 | 246 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| 1–2 | 338 | 0.7 (0.4 to 1.2) | 0.8 (0.5 to 1.5) | 0.6 (0.3 to 1.2) | 1.0 (0.5 to 2.2) | 1.3 (0.8 to 2.0) | 0.9 (0.6 to 1.4) |
| 3+ | 151 | 0.3 (0.1 to 0.8) | 0.5 (0.2 to 1.3) | 0.4 (0.2 to 1.1) | 0.6 (0.2 to 1.9) | 2.3 (1.2 to 4.6) | 0.7 (0.4 to 1.3) |
| p value for trend | 735 | 0.02 | 0.09 | 0.07 | 0.35 | 0.14 | 0.24 |
| Sex | |||||||
| Female | 355 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| Male | 380 | 1.8 (1.0 to 3.0) | 1.7 (1.0 to 2.9) | 1.8 (1.0 to 3.1) | 1.4 (0.7 to 2.6) | 1.3 (0.9 to 1.9) | 1.4 (1.0 to 2.0) |
The analyses are adjusted for all variables listed in the table (gestational age, maternal smoking, socioeconomic status, and parental history of asthma).