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.

Objective To test the effectiveness of a postpartum behavioural intervention delivered by automated text messaging in reducing weight. Design Two parallel group, multicentre, randomised controlled trial. Setting Recruitment from five areas across the United Kingdom (Belfast, Bradford, Stirling, London and Cardiff) through healthcare and community pathways, including social media. Participants A 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). Interventions 12 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 measures Primary outcome was 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 more than 5 kg, waist circumference, self-reported dietary intake, physical activity and infant feeding practices. Results 674 (75.6%) participants were included in the primary analysis. There was no 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 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 an 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). Conclusions A 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. Trial registration ISRCTN Registry ISRCTN16299220