Mapping postpartum physical activity, sedentary time, and sleep: assessing the impact of prenatal physical activity interventions in the FitMum randomized controlled trial.

Postpartum physical activity (PA) is linked to improved mental health and sleep. Yet, many women do not return to pre-pregnancy PA levels, and sedentary behavior may increase. This study mapped PA, sedentary time, and sleep from early pregnancy to one year postpartum, and examined if prenatal PA interventions affect these outcomes postpartum. In the FitMum randomized controlled trial, 220 healthy, inactive pregnant women (< 15 + 0 weeks gestation) were assigned to standard care (CON), supervised exercise (EXE), or motivational PA counselling (MOT). Participants wore wrist-worn activity trackers from inclusion to one year postpartum and completed the Pregnancy Physical Activity Questionnaire and Pittsburgh Sleep Quality Index. We found that postpartum daily steps increased by ~ 2,000 compared to late pregnancy (p < 0.001), while moderate-to-vigorous-intensity PA (MVPA) declined (p < 0.001). Sedentary time remained similar. Sleep duration dropped postpartum in the first three months (p < 0.05), while sleep quality improved (p = 0.006). Prenatal PA interventions had minimal impact postpartum, however, EXE participants reported slightly better sleep than MOT at one year. In conclusion, PA patterns and sleep changed postpartum, with more daily steps, less MVPA, and reduced sleep duration. Prenatal PA interventions had limited effect. Longitudinal studies are needed to optimize timing of interventions for maternal health. The study is registered at ClinicalTrials.gov; NCT03679130;20/09/2018.