Table 1 Summary of baseline characteristics of nontrial (group B) and trial (group A) groups taken from all self-reported smokers at maternity booking from January to December 2012
Characteristics | Nontrial group B (n = 1982) | Trial group A (n = 492) | P value |
|---|---|---|---|
CO level (ppm) for those with CO ≥7 ppm, median (interquartile range) | 12 (10–16) | 12 (10–17) | 0.98 |
Gestation (weeks), median (interquartile range) | 13.3 (11.7–15.3) | 12.9 (11.3–14.3) | <0.001a |
Deprivation quintiles, n (%) | |||
 Most deprived | |||
  1st | 1331 (67.4) | 322 (65.5) | 0.58b |
  2nd | 319 (16.2) | 83 (16.9) |  |
  3rd | 168 (8.5) | 51 (10.4) |  |
  4th | 100 (5.1) | 21 (4.3) |  |
  5th | 56 (2.8) | 15 (3.1) |  |
 Least deprived | |||
  Missing | 8 | 0 |  |
 Age under 20 | 272 (13.7) | 59 (12.0) | 0.09c |
  20–24 | 599 (30.3) | 126 (25.6) | |
  25–29 | 491 (24.8) | 136 (27.6) | |
  30–34 | 359 (18.1) | 113 (23.0) | |
  35+ | 258 (13.0) | 58 (11.8) | |
  Missing | 3 | 0 | |
BMI categories, n (%) | |||
  Underweight | 90 (4.6) | 19 (4.0) | 0.15d |
  Normal weight | 921 (47.5) | 215 (44.7) | |
  Overweight | 532 (27.5) | 139 (28.9) | |
  Obese | 395 (20.4) | 108 (22.5) | |
  Missing | 44 | 11 | |