Effectiveness and cost effectiveness of a 12 month automated text message intervention for weight management in postpartum women with overweight or obesity: protocol for the Supporting MumS (SMS) multi-site, parallel-group, randomised controlled trial.

Introduction The reproductive years can increase weight-related risk for women. Evidence for effective postpartum weight management interventions is lacking and engaging women at this time is challenging. Following a promising pilot evaluation of the Supporting MumS intervention, we assess if theory-based and bidirectional text messages to support diet and physical activity behaviour change for weight loss and weight loss maintenance, are effective and cost-effective for weight change in postpartum women with overweight or obesity, compared with an active control arm receiving text messages on child health and development. Methods and analysis Two-arm, parallel group, assessor-blind randomised controlled trial with cost-effectiveness and process evaluations. Women (n=888) with body mass index ≥25 kg/m2 and within 24 months of giving birth, recruited via community and NHS pathways through five United Kingdom sites targeting areas of ethnic and socioeconomic diversity. Women are 1:1 randomised to the intervention or active control groups, each receiving automated text messages for 12 months. Data is collected at 0, 6, 12 and 24 months. The primary outcome is weight change at 12 months from baseline, compared between-groups. Secondary outcomes include weight change (24 months) and waist circumference (cm), proportional weight gain (>5kg), BMI (kg/m2), dietary intake, physical activity, infant feeding and mental health (12 and 24 months respectively). Economic evaluation examines health service usage and personal expenditure, health-related quality of life and capability wellbeing to assess cost-effectiveness over the trial and modelled lifetime. Cost-utility analysis examines cost per quality-adjusted life years gained over 24 months. Mixed method process evaluation explores participant experiences and contextual factors impacting outcomes and implementation. Stakeholder interviews examine scale-up and implementation. Ethics and dissemination Ethical approval obtained before data collection (West of Scotland Research Ethics Service REC 4 22/WS/0003). Results will be published via a range of outputs and audiences. Trial Registration [2a]: [ISRCTN16299220][1] (prospectively registered). ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial ISRCTN16299220 ### Funding Statement This trial is supported by the NIHR Public Health Research (PHR) Programme (NIHR131509) and intervention costs provided by the Northern Ireland Public Health Agency. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: REC 4 of West of Scotland Research Ethics Service gave ethical approval for this work (reference 22/WS/0003). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors [1]: /external-ref?link_type=ISRCTN&access_num=ISRCTN16299220