Effectiveness of an automated text message intervention for weight management in postpartum women with overweight or obesity (Supporting MumS (SMS)): a UK wide, multicentre, two arm, parallel group, randomised controlled trial.

ObjectiveTo test the effectiveness of a postpartum behavioural intervention delivered by automated text messaging in reducing weight. DesignTwo parallel group, multicentre, randomised controlled trial. SettingRecruitment from five areas across the United Kingdom (Belfast, Bradford, Stirling, London and Cardiff) through healthcare and community pathways, including social media. ParticipantsA diverse sample of 892 women between 6 weeks and 24 months postpartum, aged 18 years or more and with a body mass index of 25 kg/m2 or more, enrolled between May 2022 and May 2023: 445 were randomised to the intervention and 447 to an active control (comparator). InterventionsTwelve months of fully automated text messages with embedded behaviour change techniques and two-way messaging components to support weight loss and maintenance of weight loss in the postpartum period by targeting dietary, physical activity and weight management behaviours. The comparator group received 12 months of text messages on child health and development tailored to child age. Main outcome measuresPrimary outcome - weight in kilograms at 12 months (end of intervention). Secondary outcomes recorded at 6 and 12 months were changes in weight (at 6 months), body mass index, proportions of women with weight gain or loss of 5 kg or more, waist circumference, self-reported dietary intake, physical activity and infant feeding practices. Results674 (75.6%) participants were included in the primary analysis. There was no statistically significant difference found in the adjusted mean weight change between the intervention and active control groups (-0.1 kg (95% confidence interval -1.0 to 0.8, P= 0.84). Sensitivity analyses did not change these results. There was a small statistically significant improvement in Fat and Fibre Barometer scores at 12 months in the intervention compared with control group (adjusted mean difference 0.09, 95% CI: 0.04 to 0.14; P <0.001) and a statistically significant increase in physical activity scores (International Physical Activity Questionnaire - Short Form) at 12 months in the intervention group compared with the control group (adjusted mean difference 405.3 total MET minutes/week, 95% CI: 141.3 to 669.3; P= 0.003). ConclusionsA 12 month automated, interactive behavioural weight management intervention delivered by text message did not support weight loss for postpartum women but did have a positive impact on diet and physical activity behaviours. WHAT IS ALREADY KNOWN ON THIS TOPICWomen desire support with self-care behaviours such as diet, physical activity and weight management in the postpartum period, but little support is currently available. There is a lack of acceptable and effective weight management interventions designed for women during the postpartum period. Most previous studies in the field have been affected by poor recruitment, high rates of attrition, lack of diversity and have not adequately considered the lived experience of women. Mobile technologies can offer a more flexible and individualised any time, any place approach to behavioural weight management interventions that may be well suited to this stage of life. WHAT THIS STUDY ADDSThe trial methodology was highly acceptable to postpartum women and recruitment and retention targets were met. Overall, a fully automated two-way text message intervention did not support weight loss in a diverse sample of postpartum women from the United Kingdom but did support positive changes in diet, physical activity and infant feeding behaviours. Pre-specified engagement analysis showed that women who engaged most with the intervention did lose weight. There was no differential effect of the intervention across socioeconomic or ethnic groups.