| Birth weight g | All children | Children with SDS -1–1 | ||||||
| Population | With asthma | OR (95% CI) | Population | With asthma | OR (95% CI) | |||
| <1000 | 1758 | 269 | 3.23 (2.85–3.66) | 502 | 86 | 3.78 (3.02–4.73) | ||
| 1000–1499 | 2540 | 333 | 2.68 (2.39–3.00) | 910 | 142 | 3.55 (2.48–4.23) | ||
| 1500–2499 | 19046 | 1783 | 1.91 (1.81–2.01) | 6254 | 670 | 2.20 (2.03–2.38) | ||
| 2500–2999 | 70462 | 4466 | 1.30 (1.28–1.34) | 26439 | 1881 | 1.49 (1.41–1.53) | ||
| 3000–3999 | 509075 | 27379 | 1.00 (reference) | 427043 | 22585 | 1.00 (reference) | ||
| 4000–4999 | 156838 | 8765 | 0.94 (0.92–0.97) | 35564 | 1961 | 0.94 (0.92–0.97) | ||
| 5000–6499 | 4485 | 251 | 0.88 (0.77–1.00) | |||||
| ≥6500 | 5 | 0 | ||||||
| Total | 764209 | 43264 | 496712 | 27325 | ||||
Data are presented as n, unless otherwise stated. Data were adjusted for year of birth, maternal age, parity, smoking in early pregnancy, pre-pregnancy body mass index and sex of infant. SDS: standard deviation score.