Background: Although mobile health (mHealth) interventions have demonstrated effectiveness in modifying 1 or 2 health-risk behaviors at a time, there is a knowledge gap regarding the effects of stand-alone mHealth interventions on multiple health risk behaviors. Objective: This study aimed to estimate the 2- and 4-month effectiveness of an mHealth intervention (LIFE4YOUth) targeting alcohol consumption, diet, physical activity, and smoking among Swedish high school students, compared with a waiting-list control condition. Methods: A 2-arm parallel group, single-blind randomized controlled trial (1:1) was conducted from September 2020 to June 2023. Eligibility criteria included nonadherence to guidelines related to the primary outcomes, such as weekly alcohol consumption (standard drinks), monthly frequency of heavy episodic drinking (ie, ≥4 standard drinks), daily intake of fruit and vegetables (100-g portions), weekly consumption of sugary drinks (33-cL servings), weekly duration of moderate to vigorous physical activity (minutes), and 4-week point prevalence of smoking abstinence. The intervention group had 16 weeks of access to LIFE4YOUth, a fully automated intervention including recurring screening, text message services, and a web-based dashboard. Intention-to-treat analysis was conducted on available and imputed 2- and 4-month self-reported data from participants at risk for each outcome respectively, at baseline. Effects were estimated using multilevel models with adaptive intercepts (per individual) and time by group interactions, adjusted for baseline age, sex, household economy, and self-perceived importance, confidence, and know-how to change behaviors. Bayesian inference with standard (half-)normal priors and null-hypothesis testing was used to estimate the parameters of statistical models. Results: In total, 756 students (aged 15-20, mean 17.1, SD 1.2 years; 69%, 520/756 females; 31%, 236/756 males) from high schools across Sweden participated in the trial. Follow-up surveys were completed by 71% (539/756) of participants at 2 months and 57% (431/756) of participants at 4 months. Most participants in the intervention group (219/377, 58%) engaged with the intervention at least once. At 2 months, results indicated positive effects in the intervention group, with complete case data indicating median between-group differences in fruit and vegetable consumption (0.32 portions per day, 95% CI 0.13-0.52), physical activity (50 minutes per week, 95% CI –0.2 to 99.7), and incidence rate ratio for heavy episodic drinking (0.77, 95% CI 0.55-1.07). The odds ratio for smoking abstinence (1.09, 95% CI 0.34-3.64), incidence rate ratio for weekly alcohol consumption (0.69, 95% CI 0.27-1.83), and the number of sugary drinks consumed weekly (0.89, 95% CI 0.73-1.1) indicated inconclusive evidence for effects due to uncertainty in the estimates. At 4 months, a remaining effect was observed on physical activity only. Conclusions: Although underpowered, our findings suggest modest short-term effects of the LIFE4YOUth intervention, primarily on physical activity and fruit and vegetable consumption. Our results provide inconclusive evidence regarding weekly alcohol consumption and smoking abstinence. Trial Registration: ISRCTN Registry ISRCTN34468623; https://doi.org/10.1186/ISRCTN34468623

Health promotion interventions delivered via mobile phones (mHealth) need to be carefully tailored to end-users to optimize engagement and effects on health outcomes. However, tailoring requires an in-depth understanding of the users’ context and under which circumstances end-users are willing to engage. The aim of this study was to identify and describe how high school students perceive health behaviour change and how mobile phones are used in the process of change. Thematic analysis was used to analyse data collected through 6 focus groups with 21 Swedish high school students (16–19 years). The results showed that behaviour change among adolescents were promoted by having an open approach, being able to be independent, and self-accepting. Mobile phones can provide resilience in long-term behaviour change. These findings may be useful in the development of mHealth interventions, but also for professionals in promoting healthy behaviours among adolescents.

The effectiveness of mHealth interventions rely on whether the content successfully activate mechanisms necessary for behavior change. These mechanisms may be affected by end-users’ experience of the intervention content. The aim of this study was to explore how the content of a novel mHealth intervention (LIFE4YOUth) was understood, interpreted, and applied by high school students, and the consequences of engaging with the content. Qualitative content analysis was used inductively and deductively to analyze interview data (n = 16) based on think-aloud techniques with Swedish high school students aged 16–19 years. Theoretical constructs from social cognitive theory framed the deductive analysis. The analysis resulted in four categories which describe central activities of intervention engagement among end-users: defining, considering, centralizing, and personalizing. End-users engaged in these activities to different degrees as illustrated by four typologies: Literal, Vague, Rigid, and Creative engagement. Most informants knew about the risks and benefits of health behaviors, but engagement with intervention content generally increased informants’ awareness. In conclusion, this study provides in-depth knowledge on the cognitive process when engaging with mHealth content and suggests that deliberate and flexible engagement most likely deepens end-users’ understanding of why and how health behavior change can be managed.

Background: Migrant health, including reproductive health, is an important public health priority. The postpartum period is a critical window for establishing healthy behaviors that can impact long-term health. Mobile health interventions offer a scalable solution, but existing tools are often not culturally or linguistically adapted for diverse populations. To the best of our knowledge, no previous study has evaluated the effectiveness of a culturally targeted mobile health intervention delivered after childbirth to promote a healthy diet and physical activity among migrant women. Objective: The PRIMI (Promoting Reproductive Health in Migrant Women) trial will determine the effectiveness of a smartphone app (the PRIMI app) on primary (diet quality and moderate-to-vigorous physical activity) and secondary (health literacy, BMI, self-efficacy, and self-rated health) outcomes in first-generation migrant women after childbirth. Methods: A 2-arm randomized controlled trial will be conducted to examine the effectiveness of the PRIMI app. First-generation migrant women who have given birth within 6 months, are aged 18 years or older, and prefer to receive health-related information in any of the provided languages are eligible to participate in the study and will be recruited through health care services in Sweden. The women will be randomized to the control group (standard care, eg, parental guidance and support within child health care) or the intervention group (PRIMI app+standard care) in a 1:1 ratio. A total of 200 women (100 per group) will be included in the study. A waitlist control strategy will be applied so that women in the control group will receive the PRIMI app after the follow-up measurement at 6 months. Outcomes will be assessed at baseline and at the 6-month follow-up. The PRIMI app, developed within the PRIMI project, is compatible with both Android and iOS. It contains weekly changing themes focusing on physical activity, diet, and health literacy throughout the 6-month intervention period. The app integrates behavior change techniques such as feedback and monitoring, goal setting, and instructions on how to perform the behavior. The app’s language can be switched among 4 common languages (Arabic, Somali, English, and Swedish), and all textual content can be accessed through audio files for listening. All procedures have been approved by the Swedish Ethical Review Authority (reference 2022-06733-01 and 2024-00135-02). Results: Recruitment of study participants is planned to begin in September 2025. We anticipate completing recruitment in 2026 and that the results of the PRIMI trial will be available in 2027. Conclusions: This study will provide novel evidence on the effectiveness of the PRIMI app in promoting healthy behaviors and supporting postpartum health among migrant women. This is highly relevant given the lack of previous comparable studies and the urgent need for tailored postpartum interventions for migrant populations. Trial Registration: ClinicalTrials.gov NCT06881277; https://clinicaltrials.gov/study/NCT06881277 International Registered Report Identifier (IRRID): PRR1-10.2196/79277

Introduction: Adolescence is a critical period marked by physiological and psychological changes that influence long-term health. Establishing healthy behaviors, particularly regular physical activity, is essential during this stage; however, around 80% of young people do not meet the World Health Organization’s physical activity recommendations. Digital technologies offer promising opportunities to promote health among youth, yet most physical activity apps lack scientific validation and usability. Unlike psychology, which has validated repositories to guide users in selecting mental health apps, physical activity lacks validated repository platforms, especially for adolescents. The project has a twofold aim: (1) to co-design a website, named the TeenFit website, that facilitates the selection of physical activity apps tailored to each adolescent’s individual needs and preferences; and (2) to investigate the barriers and facilitators for the implementation of the TeenFit website in real-world settings. Methods and analysis: Adolescents and other stakeholders (i.e., caregivers, educators, and health professionals) will be engaged in the development of the TeenFit website app finder through a participatory design approach that involves three workshops, encompassing both a development phase and an implementation phase. Approximately 10-12 participants per stakeholder group will take part in smaller working groups (i.e., workshops) to collaboratively contribute to the co-design of the TeenFit website. TeenFit will include mobile applications available in the Spanish market, developed in both English and Spanish. These applications are currently being identified through two ongoing systematic reviews. In addition to qualitative data gathered during the audio- and video-recorded workshops, quantitative data will be collected on participants’ co-design experiences and the acceptability of the TeenFit website. Data analysis will involve descriptive statistics, qualitative content analysis for describing participants’ perspectives on what aspects (i.e., content, features, and layout) are important for the design of the website, and reflexive thematic analysis to identify barriers and facilitators to implementation. Ethics and dissemination: The study was approved by the Research Ethics Committee in the province of Málaga (Spain) (REC ref: SICEIA-2024-003172). Research findings will be disseminated primarily via national and international conferences and publication in peer-reviewed journals. Patient and public involvement will inform further dissemination activities. Strengths and limitations of this study: The major strength of the study is that it draws on both qualitative and quantitative data to generate meaningful insights into the co-design and implementation of the TeenFit website, including participants’ co-design experiences, preferences, sociodemographic characteristics, the website’s acceptability, and the barriers and facilitators to its implementation. Limitations include the use of a convenience sampling approach, which may lead to uneven demographic representation. A transparent reporting of participant characteristics will nevertheless allow readers to assess whether our findings are transferable to other settings. Offering one-to-one online participation alongside in-person workshops may mitigate accessibility barriers, though it could affect the dynamics of group interaction compared with fully in-person sessions.

Introduction Adolescence is a critical period marked by physiological and psychological changes that influence long-term health. Establishing healthy behaviours, particularly regular physical activity, is essential during this stage; however, around 80% of young people do not meet the WHO’s physical activity recommendations. Digital technologies offer promising opportunities to promote health among youth, yet most physical activity mobile applications (apps) lack scientific validation and usability. Unlike psychology, which has validated repositories to guide users in selecting mental health apps, physical activity lacks validated repository platforms, especially for adolescents. The project has a twofold aim: (1) to co-design a website, named the TeenFit website, that facilitates the selection of physical activity apps tailored to each adolescent’s individual needs and preferences and (2) to investigate the barriers and facilitators for the implementation of the TeenFit website in real-world settings. Methods and analysis Adolescents and other stakeholders (ie, caregivers, educators, and health professionals) will be engaged in the development of the TeenFit website app finder through a participatory design approach that involves three workshops, encompassing both a development phase and an implementation phase. Approximately 10–12 participants per group will take part in smaller working groups to collaboratively contribute to the co-design of the TeenFit website. TeenFit will include physical activity apps available in the Spanish market, developed in both English and Spanish. These applications are currently being identified through two ongoing systematic reviews. In addition to qualitative data gathered during the audio- and video-recorded workshops, quantitative data will be collected on participants’ co-design experiences and the acceptability of the TeenFit website. Data analysis will involve descriptive statistics, qualitative content analysis for describing participants’ perspectives on what aspects (ie, content, features and layout) are important for the design of the website and reflexive thematic analysis to identify barriers and facilitators to implementation. Ethics and dissemination The study was approved by the Research Ethics Committee in the province of Málaga (Spain) (REC ref: SICEIA-2024-003172). Research findings will be disseminated primarily via national and international conferences and publication in peer-reviewed journals. Patient and public involvement will inform further dissemination activities.