Behavior Reallocations Within 24-hour Movement Profiles And Postpartum Mental Health

PURPOSE: Postpartum moderate/vigorous intensity physical activity (MVPA) is recommended. It is unclear whether reallocating time to MVPA from sleep, sedentary time (SED), or light intensity physical activity (LPA) is equally beneficial for postpartum mental health. This study described associations of theoretical behavior reallocations to MVPA and postpartum mental health. METHODS: We used data from postpartum individuals at high risk for depression (n = 70). At mean 4 months postpartum (baseline), 24-hour movement was measured using wrist-worn accelerometers (7 days), categorized into sleep, SED, LPA, and MVPA using Tracy and Hibbing algorithms, and averaged and normalized to 24 hours. Depressive (PHQ-8) and anxiety (GAD-7) symptoms were measured at baseline and 3 months later. We used compositional isotemporal substitution models to estimate associations of theoretically reallocating time to MVPA from other behaviors, from an initial 24-hour movement profile with low MVPA (0.1%, 1 minute). RESULTS: On average, depressive and anxiety symptoms decreased by 1.8 and 2.5 points, respectively, over 3 months of follow-up. Associations of reallocating up to 30 minutes of any behavior to MVPA with change in depressive and anxiety symptoms were not statistically significant (Figure, all P > 0.05). However, point estimates were in the small to moderate effect range for depressive symptoms, suggesting that reallocating 30 minutes of sleep, SED, or LPA to MVPA may be associated with 1.6 (95% CI: -7.7,4.4), 1.4 (95% CI: -7.3, 4.4), and 2.2 (95% CI: -9.0, 4.5) point greater decrease in depressive symptoms, respectively. CONCLUSION: Our exploratory findings suggest that increasing MVPA to guideline-recommended amounts in postpartum may be beneficial for reducing depressive symptoms in those at high risk for depression; however, adequately powered studies are needed to better understand these associations.Kaiser Permanente Exercise as Medicine Research Program