Effectiveness and cost effectiveness of an automated text message intervention for weight management in postpartum women with overweight or obesity: the Supporting MumS (SMS) Randomised Controlled Trial

RESEARCH QUESTION: Does a fully automated text message intervention support weight loss and maintenance of weight loss in women with overweight or obesity who have had a baby in the last two years?

BACKGROUND: Women are at an increased risk for weight gain during the reproductive years. Weight loss interventions are needed to support postpartum women to improve their health before future pregnancies. Our NIHR-funded pilot RCT showed that a text message delivered intervention might work well for this group.

AIMS:

1.To adapt the text message library to ensure broad acceptability across different ethnic groups and the four countries in the UK.

2.To conduct a 2-arm parallel group RCT comparing weight change at 12 months for postpartum women with overweight or obesity who receive text messages about weight management or an active control. 3.To assess differences between groups in secondary outcomes.

4. To assess the prevalence and trajectories of postnatal mental health in women across the UK, particularly those from marginalised groups, including assessment of the mother-child relationship. 5.To assess the cost-effectiveness of the text message intervention.

6. To conduct a process evaluation to explore women’s experiences of the intervention, the pathways through which the intervention effects are mediated and contextual factors affecting the outcomes or future implementation of the intervention, including the impact of postnatal mental health on intervention engagement and outcomes.

7. To seek permission for linkage to routine data for long term health outcomes (mum and youngest baby).

8. To examine the effect of the 12 month intervention in the longer-term, at 24 months (i.e. 12 months after the intervention has ceased). 9. To conduct interviews with stakeholders to explore scale-up and implementation.

RESEARCH DESIGN: A UK-wide multi-site, 2-arm, parallel RCT, with embedded process evaluation and cost-effectiveness analysis. INTERVENTION: Fully automated 12 month text message intervention for weight loss and maintenance of weight loss. ACTIVE CONTROL: Text messages about child health and development for 12 months.

POPULATION: Women with Body Mass Index greater than or equal to 25 kg/m2 who have had a baby in the last 2-years. RECRUITMENT: n=888 women via community-based approaches, social media and routine contact with health professionals. SETTING: Five sites - Scotland, N.Ireland, Wales, England (Bradford, London).

OUTCOME MEASURES: 0, 6, 12 & 24 months. Collected at home visits. Primary outcome: weight loss at 12 months.

Secondary outcomes: Proportion of women gaining a substantial amount of weight (>5kg) during the 12 and 24 month follow-up, change in waist circumference, change in dietary intake, change in physical activity and infant feeding practices. Exploratory outcomes: As part of the process evaluation, a moderator (factors that influence response to intervention) and mediator (possible mechanisms that bring about behaviour change) analysis will be conducted.

PROCESS EVALUATION: Reach, acceptability, engagement, perceived benefits, perceived mechanisms of impact, factors important for implementation; from study records and interviews with women at 6 & 12 months (n=50).

COST-EFFECTIVENESS: An economic evaluation will be will be conducted using a National Health Service and personal social services perspective with an additional societal perspective applied to capture the broader impact, adhering to guidance for conducting public health economic evaluations.

TIMELINE: M 0-6 - Set up, cultural adaptation of text message library with PPI; M 7-24 - Recruitment & 6 month follow-up; M 19-30 – 12M follow-up; M 31-42 – 24M follow-up; M 43-46 - Completion of data analysis, final report, dissemination (ongoing from M30).

ANTICIPATED IMPACT & DISSEMINATION: If successful, this postpartum weight management intervention could be implemented throughout the UK to reduce lifelong excess weight in women. The findings will be disseminated widely to women, health professionals, policy makers, service commissioners and academics.