Table 1.
Characteristics of the cohort (N = 850)
| Characteristic | Mean (SD) |
|---|---|
| Gestation (weeks) (n = 806) | 15.6 (4.1) |
| Age (n = 847) | 25.8 (5.6) |
| Perceived stress scale (PSS-4) (n = 819) | 10.6 (3.5)* |
| n (%)** | |
| Qualifications: GCSEs or similar*** | 594/850 (69.9) |
| Home ownership | 166/846 (19.6) |
| Cars or vans available for use in household | 446/839 (53.2) |
| In paid work | 383/850 (45.1) |
| Ethnicity: Caucasian | 783/844 (92.8) |
| Baseline smoker | 488/850 (57.4) |
| First pregnancy | 275/839 (32.8) |
| If pregnant before, smoked during last pregnancy | 368/561 (65.6) |
| Owns a mobile phone | 776/797 (97.4) |
| Owns a smartphone | 547/774 (70.7) |
| Mobile phone bundle includes free text messages | 610/778 (78.4) |
*Maximum score on PSS-4 is 16.
**Numbers may not add up to 850 (total sample size) due to missing data.
***General Certificate of Secondary Education (GCSE) is a qualification/exam taken by school students in the United Kingdom (except Scotland) usually when aged between 14 and 16 years old.