Digital Interventions Targeting Parents to Improve Early Childhood Movement, Nutrition, and Sleep Behaviors: Systematic Review.

Background: Early childhood (0-5 years) is key for shaping health behaviors, yet optimal behaviors are rarely achieved. Digital health promotion interventions offer scalable support for families; however, most research has focused on childhood more broadly, leaving limited evidence for the early childhood period. Objective: The primary aim of this systematic review was to examine whether autonomously delivered digital interventions targeting parents are effective at increasing physical activity, reducing sedentary behavior, improving nutrition (breastfeeding, feeding practices), and/or optimizing sleep among children aged 0-5 years. The secondary aim was to review the reporting of co-design practices, user engagement, and process evaluation, and to assess how engagement influences intervention effectiveness. Methods: Seven databases were searched for randomized controlled trials (RCTs) evaluating autonomously delivered digital interventions targeting one or more of the following behaviors: physical activity, sedentary behavior, nutrition, or sleep among children (published to January 2026). Study quality was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for RCTs. Findings were narratively synthesized by target age-group and behavior, and the direction of effect was summarized in structured tables. Results: Of the 14,352 identified records, 38 interventions (33 RCTs, 4 pilot RCTs, and 1 feasibility RCT) were included. Most studies focused on pregnancy to infancy (n=24; 0-1 y), followed by preschoolers (n=8; 3-5 y) and toddlers (n=6; 1-2 y). Intervention duration ranged from 2 weeks to 1000 days, and various digital formats were used (apps n=11, SMS text messaging n=10, web- or internet-based platforms n=6, WeChat [Tencent] n=3, tablet-based program n=2, a combination of app and SMS text messaging n=1, website and emails n=1, emails and SMS text messaging n=1, automated voice calls n=1, Facebook Messenger Chatbot [Meta] n=1, and online videos n=1). Interventions spanning pregnancy to infancy reported mixed findings for breastfeeding and feeding practices. Studies targeting toddlers showed improvements in sleep, mixed findings for diet and screen time, and no differences in physical activity. Most studies targeting preschoolers reported significant improvements for feeding practices and diet, but no differences in physical activity, sedentary behavior and sleep, and mixed findings for screen time. Most studies reported co-design or engagement (n=24), but few examined the impact of engagement on intervention effectiveness (n=6), and those that did reported mixed findings. Interpretation was limited by heterogeneous designs, inconsistent outcome measures, and mixed risk-of-bias ratings across studies. Conclusions: This review advances the field by synthesizing evidence on scalable digital interventions that support parents in promoting healthy lifestyle behaviors across the first 2000 days, together with key design and implementation factors that have rarely been reported in previous reviews. Unlike prior work, it focuses exclusively on autonomously delivered digital interventions in early childhood. Findings show heterogeneous designs and mixed effectiveness, and highlight 3 priority evidence gaps: limited studies in toddlers and preschoolers, incomplete reporting of engagement, and limited understanding of how engagement influences outcomes. These findings define priorities for future research to strengthen the evidence for scalable digital interventions in early childhood.