Generalizability, strengths, and limitations
This was an effectiveness trial with the intention of being as close to real-world circumstances as possible, within the limits of necessary trial procedures. As families were recruited from 19 child health care centers in six Swedish regions, covering various geographic and socioeconomic contexts, the generalizability of our findings is high in comparison to previously conducted efficacy trials. We also translated and adapted the app into Somali, Arabic and English to reach as many families in the Swedish population as possible. Our efforts were successful; compared to the first MINISTOP trial, where only 9% of children had parents born outside Sweden [The study also has some limitations. Since the nurses provided access to the app, they were not blinded to the group allocation which may be a limitation as it introduces the possibility of nurses providing additional information on healthy eating and physical activity to the control group participants knowing they would not receive the app. This may dilute the true effect, however, all nurses were pre-trained in the study protocol by the research team and hence we consider this risk as unlikely. Also, data imputation, processing, and analyses were conducted by the research team. Thus, we do not consider that non-blinded assessors had any major influence on our findings. Another limitation was the use of self-reported outcome data, which may be subject to recall bias but also social desirability bias as parents were not anonymous when reporting their child’s health behaviors in the questionnaire, and thus may have reported healthier behaviors than they actually had. Furthermore, even though a well-established and validated questionnaire was used [