Table 1 Maternal characteristics by smoking status (unadjusted for sample weighting)
| Maternal Characteristics | Non-smoker, non ETS exposed (n = 8100) | Non-smoker, ETS exposed (n = 2259) | Active smoker (n = 6397) | Excluded due to missing smoking data (n = 1541) |
|---|---|---|---|---|
| Maternal age at birth Mean (SD) | 29.6 (5.6) | 28.7 (5.5) | 26.2 (6.0) | 29.2 (5.8) |
| BMI Mean (SD) | 24.0 (4.4) | 24.0 (4.8) | 23.2 (4.4) | 23.8 (4.4) |
| Parity (previous live births) N (%) * | ||||
| None | 3310 (42.2) | 862 (40.1) | 2838 (45.2) | 496 (36.0) |
| 1–2 | 3952 (50.4) | 1083 (50.4) | 2882 (45.9) | 750 (54.5) |
| 3 or more | 572 (7.3) | 203 (9.4) | 553 (8.8) | 131 (9.5) |
| Alcohol use in pregnancy N (%) | 622 (7.7) | 157 (7.0) | 684 (10.7) | 98 (6.6) |
| Ethnicity N (column %) * | ||||
| White | 6501 (80.4) | 1701 (75.4) | 6058 (94.9) | 1018 (68.2) |
| Asian | 872 (10.8) | 412 (18.3) | 76 (1.2) | 364 (24.4) |
| Black | 438 (5.4) | 43 (1.9) | 117 (1.8) | 64 (4.3) |
| Mixed or other | 275 (3.4) | 100 (4.4) | 134 (2.1) | 46 (3.1) |
| Education N (column %) * | ||||
| Degree | 1942 (24.0) | 320 (14.2) | 351 (5.5) | 247 (16.4) |
| Diploma or A level | 1714 (21.2) | 440 (19.5) | 789 (12.4) | 278 (18.5) |
| O levels | 3090 (38.2) | 938 (41.6) | 3401 (53.3) | 633 (42.1) |
| None of the above | 1342 (16.6) | 558 (24.7) | 1840 (28.8) | 347 (23.1) |
| Income (£) N (column %) * | ||||
| Less than 10,400 | 1482 (19.9) | 424 (20.3) | 2514 (42.2) | 256 (20.9) |
| 10,400 to 20,800 | 2194 (29.5) | 835 (40.0) | 2058 (34.5) | 453 (37.0) |
| 20,800 to 31,300 | 1723 (23.2) | 469 (22.5) | 822 (13.8) | 240 (19.6) |
| Above 31,200 | 2035 (27.4) | 358 (17.2) | 568 (9.5) | 277 (22.6) |
