Characteristics of the 774 respondents by smoking status (mean (SD) or percentage (n))
| Non-smokers (n=461) | Smokers (n=313) | p Value of difference | |
|---|---|---|---|
| Mean (SD) | |||
| Age (y) | 26.6 (4.6) | 24.5 (5.2) | <0.001 |
| Height (cm)1-150 | 164.3 (6.3) | 164.3 (6.7) | 0.936 |
| Weight before pregnancy (kg)† | 63.5 (13.3) | 61.4 (11.9) | 0.032 |
| Weight at time of interview (kg)‡ | 67.3 (12.7) | 65.7 (11.6) | 0.080 |
| Body mass index at interview (kg/m2) | 24.9 (4.3) | 24.3 (4.1) | 0.064 |
| Diastolic blood pressure at interview (mm Hg)§ | 66 (8) | 65 (9) | 0.007 |
| Gestational age at booking (weeks) | 16.3 (1.3) | 16.4 (1.4) | 0.309 |
| Social class∥ | % (n) | ||
| I and II | 39.5 (182) | 26.2 (82) | <0.0001 |
| IIINM | 34.9 (161) | 32.3 (101) | |
| IIIM | 17.1 (79) | 19.5 (61) | |
| IV and V | 5.9 (27) | 18.8 (59) | |
| Unemployed/ student/caring for home | 2.6 (12) | 3.2 (10) | |
| Education | |||
| No qualifications | 2.8 (13) | 13.1 (41) | <0.0001 |
| Up to CSE equivalent | 10.6 (49) | 18.5 (58) | |
| Up to O level equivalent | 53.1 (245) | 52.4 (164) | |
| Up to A level equivalent | 8.5 (39) | 4.8 (15) | |
| Up to further education | 16.1 (74) | 7.7 (24) | |
| Up to degree or higher | 8.9 (41) | 3.5 (11) | |
↵1-150 Height unknown for one mother. †32 mothers could not recall their weight before pregnancy. ‡Weight at booking unknown for 22 mothers. §Blood pressure not recorded for 9 women. ∥Test performed across classes I to V.