Association of participant characteristics with maternal physical activity during pregnancy: using multiply imputed data (N=4665) of individuals with data for maternal physical activity (exposure) and at least one outcome
| Potential confounder | Confounder category | SD change of maternal physical activity during pregnancy associated with a 1 SD increase of confounder, with 95% CI |
|---|---|---|
| Household social class* | Class I (professional) | Reference |
| Class II | 0.00 (−0.08 to 0.09) | |
| Class III non-manual | −0.18 (−0.27 to −0.09) | |
| Class III manual | −0.16 (−0.28 to −0.04) | |
| Class IV/V (manual) | −0.15 (−0.31 to 0.01) | |
| Maternal education† | Less than O-level | Reference |
| O-level | 0.17 (0.09 to 0.25) | |
| A-level | 0.39 (0.30 to 0.47) | |
| Degree or above | 0.40 (0.30 to 0.49) | |
| Ethnicity‡ | Non-white | Reference |
| White | −0.11 (−0.25 to 0.03) | |
| Parity§ | 0 | Reference |
| 1 | −0.05 (−0.11 to 0.02) | |
| 2+ | −0.10 (−0.19 to −0.02) | |
| Maternal smoking in pregnancy | No | Reference |
| Yes | −0.09 (−0.17 to −0.01) | |
| Previous hypertension | No | Reference |
| Yes | −0.03 (−0.17 to 0.12) | |
| Maternal prepregnancy BMI (SD) | −0.39 (−0.58 to −0.20) | |
| Gestational weight gain 0–18 weeks (SD) | −0.00 (−0.03 to 0.03) |
*Household social class: The mother recorded the occupation of both herself and her partner in a questionnaire at 32 weeks gestation, which were used to allocate them to social class groups using the 1991 Office of Population, Censuses and Surveys classification; the highest class of the mother and her partner was used in analysis.
†Maternal education: O-level (ordinary level) exams are taken in different subjects usually at age 15–16 at the completion of legally required school attendance, equivalent to today's General Certificate of Secondary Education; A-level (Advanced-level) exams are taken in different subjects usually at age 18.
‡Ethnicity: Mixed was recoded as non-white due to the small numbers in the mixed category (n=3).
§Parity: Obtained from obstetric records. Mothers with parity of two or more were grouped into a single category.
BMI, body mass index.