Measuring physical activity in pregnancy: a comparison of accelerometry and self-completion questionnaires in overweight and obese women.

OBJECTIVES: Increased physical activity in pregnancy may reduce the risk of gestational diabetes and pre-eclampsia, which occur more commonly in overweight and obese women. There is limited assessment of physical activity questionnaires in pregnancy. This study compares self-reported physical activity using two questionnaire methods with objectively recorded physical activity using accelerometry in overweight and obese pregnant women.

STUDY DESIGN: 59 women with booking BMI≥25 kg/m(2) completed the Recent Physical Activity Questionnaire (RPAQ) and Australian Women's Activity Survey (AWAS) or recorded at least 3 days of accelerometry at median 12 weeks' gestation. Accelerometer thresholds of 100 counts/min and 1952 counts/min were used to define light and moderate or vigorous physical activity (MVPA) respectively.

RESULTS: 48% of women were in their first pregnancy and 41% were obese. Median daily self-reported MVPA was significantly higher for both AWAS (127 min, p<0.001) and RPAQ (81 min, p<0.001) than that recorded by accelerometer (35 min). There was low or moderate correlation between questionnaire and accelerometer estimates of total active time (AWAS ρ=0.36, p=0.008; RPAQ ρ=0.53, p<0.001) but no significant correlation between estimates of time spent in MVPA.

CONCLUSIONS: These self-report questionnaires over-estimated MVPA and showed poor ability to discriminate women on the basis of MVPA. Accelerometry measurement was feasible and acceptable. Objective methods should be used where possible in studies measuring physical activity in pregnancy. Questionnaires remain valuable to define types of activity.