Table 1.
Baseline characteristics, according to study group. Values are numbers (percentages) unless stated otherwise
| Characteristics | Physical activity group (n=391) | Control group (n=393) |
|---|---|---|
| Mean (SD) age (years) | 27.2 (6.1) | 27.8 (6.5) |
| Mean (SD) age at leaving full time education (years)* | 17.8 (3.0) | 18.0 (3.3) |
| Mean (SD) weight (kg)† | 69.2 (14.1) | 70.9 (15.9) |
| Mean (SD) body mass index (kg/m2)† | 25.6 (5.0) | 26.6 (5.6) |
| Mean (SD) gestational age (weeks) | 15.6 (3.3) | 15.6 (3.3) |
| Mean (SD) Edinburgh postnatal depression scale score | 7.6 (5.3) | 7.7 (5.0) |
| Median (interquartile range) No of cigarettes smoked daily before pregnancy | 20 (12-20) | 20 (12-20) |
| Median (interquartile range) No of cigarettes smoked daily at randomisation | 10 (5-12) | 10 (5-15) |
| Median (interquartile range) Fagerström test of cigarette dependence score‡ | 4 (2-5) | 4 (2-5) |
| Median (interquartile range) expired carbon monoxide level (ppm)§ | 10 (7-14) | 10 (6-14) |
| Median (interquartile range) self report of weekly moderate-vigorous physical activity (mins) | 210 (125-350) | 225 (130-360) |
| Married or living with partner | 230 (59) | 221 (56) |
| Partner smokes¶ | 261 (67) | 250 (64) |
| White** | 308 (79) | 298 (76) |
| Professional or managerial occupation | 46 (12) | 53 (13) |
| Smoked in a previous pregnancy†† | 186 (78) | 193 (78) |
| Edinburgh postnatal depression scale score ≥13 | 68 (17) | 75(19) |
| Self report of ≥150 mins/week of moderate-vigorous physical activity | 275 (70) | 273 (69) |
| Self report of walking as main type of physical activity | 301 (77) | 313 (80) |
| Parity§§: | ||
| 0-1 | 317 (81) | 309 (79) |
| 2-3 | 67 (17) | 75 (19) |
| >4 | 7 (2) | 9 (2) |
| Previous preterm birth‡‡ | 68 (17) | 61 (16) |
| Very or extremely high confidence for quitting smoking | 89 (23) | 98 (25) |
| Very or extremely confident of doing 30 mins of physical activity on at least 5 days a week during pregnancy | 274 (70) | 277 (71) |
| Takes alcohol more than twice a week | 6 (2) | 5 (1) |
| Consumes >3 alcoholic drinks on a drinking day¶¶*** | 14 (16) | 3 (4) |
Baseline data were not recorded for one participant in physical activity group who withdrew consent shortly after randomisation.
*Data exclude 41 women who were still in full time education.
†Not recorded for one participant in control group.
‡Not recorded for one participant in physical activity group.
§Not recorded for one participants in physical activity group and two in control group.
¶Excludes 92 women with no partner.
**Race or ethnic group was self reported and categorised according to standard UK census categories.
††Excludes 297 with no previous pregnancies.
‡‡Any previous pregnancy of duration 24-37 weeks.
§§Number of previous pregnancies progressing beyond 24 weeks.
¶¶Excludes 617 women responding “not applicable” (that is, not consuming alcohol).
***Significant difference between groups (P=0.011), using Fisher’s exact test. This variable was not related to the primary outcome and therefore was not adjusted for in the analysis. There were no other significant differences between the groups.