Enhancing the Scalability and Impact of the Motherly App for Postnatal Depression

We read with great interest Dr. Zuccolo and colleagues' [1] article on the effect of the Motherly app on postnatal depression. We commend the authors for their methodological rigor, particularly in robust blinding and the use of an active control condition. Our letter aims to complement the study's findings by addressing factors (e.g., mechanisms or active treatment components, reporting adverse events) that may enhance Motherly's efficacy and scalability while ensuring its safety. It is important to acknowledge that some of our points may also apply broadly to other psychological interventions.First, Motherly included multiple treatment components. However, the relative contribution of each component remains unclear. Future research could apply a dismantling design to assess the efficacy of individual components. This approach isolates or removes specific elements of the intervention to identify those critical for its effectiveness [2]. For instance, comparing the current version of Motherly to a version without the sleep hygiene module could help determine whether sleep hygiene independently contributes to symptom improvement. Such studies would help retain only the essential features of Motherly, ultimately reducing development and maintenance costs and improving scalability.Another area for improvement pertains to the measurement of app engagement. Relying solely on the number of behavioral activation-related activities logged missed the nuances of app engagement. Other important forms of engagement, such as time spent exploring modules and frequency of use, may also play a role in the efficacy of Motherly [3]. Future research should incorporate these additional indices of engagement. This would provide insights into which features or modules of Motherly are most and least engaging and effective, helping developers identify areas to retain and those requiring improvement.Third, while the study assessed the overall efficacy of Motherly, it did not explore potential variations in its effects across different sociodemographic groups. Future research should investigate how baseline characteristics (e.g., education, family income, and relationship status) assessed in the study influence the engagement and outcomes of Motherly [4]. This could help inform more targeted versions of Motherly tailored to the specific needs of distinct sociodemographic groups.The authors highlighted the potential role of human support in boosting the engagement and efficacy of Motherly. Future research could use an additive design to assess the incremental benefits of adding human support [2]. In this design, components are systematically added to a base intervention to evaluate how each element enhances overall efficacy. Future studies should also compare the cost-effectiveness of adding human support to Motherly versus using Motherly alone. This comparison would help identify the most viable versions of Motherly for real-world clinical implementation and dissemination.Lastly, the study did not report potential adverse events associated with Motherly. Unintended consequences, such as misinterpretation of intervention strategies, experiencing frustration from unmet expectations, or over-reliance on Motherly at the expense of seeking professional care, may potentially occur and exacerbate symptoms during the use of Motherly. Future trials of Motherly should systematically track and report adverse events to ensure a comprehensive evaluation of both benefits and risks [5].The authors have no conflicts of interest to declare.This study was not supported by any sponsor or funder.Q.X.: conceptualization, writing – original draft, and writing – review and editing. W.C.: writing – review and editing.