Descriptive statistics of subjects with information on gran-maternal smoking during pregnancy (maternal and/or paternal) stratified by age-group: children (>4 year and <18 year) and adults (≥18 year and ≤50 year)
| Children | Adults | P value | |
| N | 11 544 | 25 747 | |
| Age, years | 10.5 (3.7) | 31.0 (8.4) | <0.001 |
| Male gender | 5638 (48.8) | 9829 (38.2) | <0.001 |
| Grandmaternal smoking | |||
| Maternal | 2501 (24.4) | 1410 (6.6) | <0.001 |
| Paternal | 1374 (18.8) | 686 (4.8) | <0.001 |
| Maternal smoking | 1226 (11.5) | 4755 (20.8) | <0.001 |
| Asthma | 1214 (11.4) | 2805 (11.0) | 0.316 |
| Early childhood asthma | 967 (9.3) | 1054 (4.4) | <0.001 |
| Spirometry performed | 7058 (61.1) | 17 901 (69.5) | <0.001 |
| FEV1 % predicted | 95.2 (10.4) | 95.2 (11.1) | 0.732 |
| FVC % predicted | 96.3 (10.0) | 98.6 (10.6) | <0.001 |
| FEV1/FVC | 0.86 (0.06) | 0.80 (0.07) | <0.001 |
| FEV1/FVC % predicted | 98.2 (7.1) | 96.0 (7.2) | <0.001 |
| Active smoking | |||
| Never | 10 909 (95.7) | 14 322 (58.7) | |
| Ex | 98 (0.9) | 4463 (18.3) | <0.001 |
| Current | 391 (3.4) | 5616 (23.0) | |
| ETS in childhood | |||
| No | 7600 (71.0) | 9831 (39.7) | |
| Yes | 2045 (19.1) | 14 785 (59.7) | <0.001 |
| Unknown | 1056 (9.9) | 148 (0.6) | |
| Maternal age, years | 29.8 (4.1) | 26.9 (4.1) | <0.001 |
| Birth weight, g | 3499.1 (616.0) | 3434.7 (580.9) | <0.001 |
| Gestational age, years | 39.6 (2.0) | 39.8 (1.8) | <0.001 |
| Breast feeding | |||
| No | 1967 (18.5) | 6157 (25.0) | |
| Yes | 8677 (81.4) | 17 485 (71.0) | <0.001 |
| Unknown | 10 (0.1) | 977 (4.0) | |
| Income | |||
| <1000 | 167 (1.4) | 4755 (18.5) | |
| 1000–2000 | 1317 (11.4) | 5297 (20.6) | |
| 2000–3000 | 3763 (32.6) | 6204 (24.1) | <0.001 |
| >3000 | 5286 (45.8) | 6708 (26.1) | |
| other | 1004 (8.7) | 2781 (10.8) | |
| Education | |||
| Low | 406 (3.5) | 1613 (6.3) | |
| Intermediate | 5579 (48.4) | 14 359 (55.8) | <0.001 |
| High | 5499 (47.7) | 9437 (36.7) | |
| Other/unknown | 54 (0.5) | 336 (1.3) |
ETS, environmental tobacco smoke.