Six-month intervention effect of a digital movement behavior intervention on parent- and child intermediary outcomes-results from the Let's Grow randomized controlled trial.

Background: Parental-focused interventions often aim to improve child health behaviors by changing parenting practices and cognitions and supporting child skill development. These intermediary outcomes serve as milestones that indicate progress towards achieving the ultimate intervention goal; however, the impact on these is rarely reported. The aim of this study was to investigate the effect of a digital intervention, intended to help parents promote healthy movement behaviors in toddlers on these intermediary outcomes.

Methods: This study utilized data from the Let's Grow trial (n = 1165). Participants were recruited Australia-wide and randomized to usual care (routine child healthcare visits) or intervention (usual care plus Let's Grow app) following baseline assessment. Participants with data on at least one intermediary outcome (assessed via an online survey) at baseline and mid-intervention (6-months) were included (usual care, n = 618; intervention, n = 547). These included parental cognitions (knowledge, self-efficacy, confidence) and behaviors (co-participation, role modelling, family rules and routines, screens in child's bedroom), and child developmental skills (motor skills, emotional regulation). Linear regression compared between-group outcomes. We also explored whether changes in the intermediary outcomes were associated with intervention engagement (Web app analytics).

Results: The intervention group had higher knowledge of child movement behaviors (mean difference = 0.41, P = 0.002) compared to control. This difference was driven by knowledge in physical activity (mean differences 0.12, P = 0.028) and sleep (mean difference 0.27, P = 0.003) topics. No significant effect was observed for the other intermediary outcomes. Higher engagement was associated with improvements in parental knowledge of child movement behaviors and physical activity, confidence, ease of parenting, family rules for movement behaviors and screen time, and less parental screen time (all P ≤ 0.039).

Conclusions: While Let's Grow positively influenced physical activity and sleep knowledge at the mid-intervention point, our findings suggests that parents might need more time or support to improve cognitions and behaviors related to children's sedentary behavior/screen time and child developmental skills. Further clarity on whether the observed changes translate into differential impacts on child movement behaviors will be reported following trial conclusion. Engagement appears to enhance intervention effects, highlighting the importance of strategies to optimize engagement.

Trial Registration: ACTRN12620001280998; U1111-1252-0599.