Maternal pre-pregnant body mass index and physical activity during pregnancy assessed by accelerometer

Abstract Background Maternal pre-pregnant overweight and obesity increase the risk of adverse pregnancy outcomes, while physical activity during pregnancy beneficially affects both the mother and the fetus. Limited data are available on how maternal pre-pregnant overweight and obesity may affect physical activity during pregnancy. Objective The purpose of this study was to describe associations between pre-pregnant body mass index (BMI) and physical activity during pregnancy. Study Design An observational prospective cohort study of 400 singleton pregnant women who attended Aarhus University Hospital, Denmark (2010-2015) was conducted. Physical activity was assessed by an accelerometer (Sensewear Armband) for seven days each trimester. Participants were stratified in three different groups of pre-pregnant BMI: normal weight (BMI 3MET) and time in vigorous intensity physical activity (>6MET). Linear regression and multilevel mixed-effects models were used to explore the association between pre-pregnant BMI and physical activity variables during pregnancy. Results We found an inverse linear relationship between pre-pregnant BMI and both mean number of steps per day and mean MET per day (p Conclusion Maternal physical activity measured by accelerometer decreased across pregnancy independently of maternal BMI status, and was inversely associated with pre-pregnant BMI. Thus, overweight or obese prior to gestation were at increased risk of sedentary behavior during pregnancy.