| Nonasthmatic | Asthmatic | Total | |
| Subjects n | 166 517 | 11 512 | 178 029 |
| Gestational age weeks | |||
| Nonsmoker | 39±2 | 39±2 | 39±2 |
| Smoker | 39±2 | 38±2 | 39±2 |
| Very preterm birth# | 2467 (1.5) | 197 (1.7) | 2664 (1.5) |
| Nonsmoker | 1789 (1.3) | 112 (1.3) | 1901 (1.3) |
| Smoker | 678 (2.4) | 85 (3.0) | 763 (2.5) |
| Preterm birth¶ | 10 311 (6.2) | 904 (7.9) | 11 215 (6.3) |
| Nonsmoker | 7684 (5.8) | 544 (6.5) | 8228 (5.8) |
| Smoker | 2627 (9.4) | 360 (12.7) | 2987 (9.7) |
| Birth weight g | 3382±594 | 3350±610 | 3306±572 |
| Nonsmoker | 3436±567 | 3437±571 | 3436±568 |
| Smoker | 3179±605 | 3135±621 | 3175±619 |
| Birth weight centile | 48.5±29.6 | 48.4±30.2 | 47±29 |
| Nonsmoker | 51±29.2 | 52.4±29.6 | 51.4±29.4 |
| Smoker | 37.4±28.6 | 37.5±28.9 | 37.4±28.6 |
| IUGR+ | 6256 (3.8) | 484 (4.2) | 6740 (3.8) |
| Nonsmoker | 3944 (3.0) | 231 (2.8) | 4175 (2.9) |
| Smoker | 2312 (8.3) | 253 (8.9) | 2565 (8.4) |
| SGA§ | 17 973 (10.8) | 1393 (12.1) | 19 366 (10.9) |
| Nonsmoker | 12 140 (9.1) | 788 (9.5) | 12 928 (9.1) |
| Smoker | 5833 (20.9) | 605 (21.4) | 6438 (21.0) |
| Neonatal intensive care required | 3235 (1.9) | 282 (2.4) | 3517 (2.0) |
| Nonsmoker | 2468 (1.9) | 185 (2.2) | 2653 (1.9) |
| Smoker | 767 (2.8) | 97 (3.4) | 864 (2.8) |
| Length of stay days median±sd | |||
| Nonsmoker | 5±18 | 5±17 | |
| Smoker | 6±21 | 8±26 | |
| Paediatric intensive care required | 366 (0.2) | 30 (0.3) | 396 (0.2) |
| Nonsmoker | 285 (0.2) | 22 (0.3) | 307 (0.2) |
| Smoker | 81 (0.3) | 8 (0.3) | 89 (0.3) |
| Length of stay days median±sd | |||
| Nonsmoker | 62±7 | 8±23 | |
| Smoker | 7±35 | 14±27 | |
| Prolonged hospital stayƒ | 2311 (1.4) | 207 (1.8) | 2518 (1.4) |
| Nonsmoker | 1584 (1.2) | 112 (1.3) | 1696 (1.2) |
| Smoker | 727 (2.6) | 95 (3.4) | 822 (2.7) |
| Resuscitation required | 14 103 (8.5) | 1178 (10.3) | 15 284 (1.4) |
| Nonsmoker | 11 227 (8.4) | 834 (10.0) | 12 064 (8.5) |
| Smoker | 2876 (10.3) | 344 (12.1) | 3220 (10.5) |
| Oxygen therapy## | 8381 (5.0) | 712 (6.2) | 9093 (5.1) |
| Nonsmoker | 6648 (5.0) | 484 (5.8) | 7132 (5.0) |
| Smoker | 1733 (6.2) | 228 (8.1) | 1961 (6.4) |
| Stillbirth | 953 (0.6) | 61 (0.5) | 1014 (0.6) |
| Nonsmoker | 724 (0.5) | 39 (0.5) | 763 (0.5) |
| Smoker | 229 (0.8) | 22 (0.8) | 251 (0.8) |
| Neonatal death¶¶ | 355 (0.2) | 24 (0.2) | 379 (0.2) |
| Nonsmoker | 285 (0.2) | 16 (0.2) | 301 (0.2) |
| Smoker | 70 (0.3) | 8 (0.3) | 78 (0.3) |
| Congenital abnormalities | 3699 (2.2) | 316 (2.7) | 4015 (2.3) |
| Nonsmoker | 3025 (2.3) | 232 (2.8) | 3257 (2.3) |
| Smoker | 674 (2.4) | 84 (3.0) | 758 (2.5) |
Data are presented as mean±sd or n (%), unless otherwise stated. IUGR: intrauterine growth restriction; SGA: small for gestational age. #: ≤32 weeks; ¶: <37 weeks; +: below the third centile; §: below the 10th centile; ƒ: >28 days; ##: >4 h; ¶¶: <28 days.