Lifestyle information and commercial weight management groups to support maternal postnatal weight management and positive lifestyle behaviour: the SWAN feasibility randomised controlled trial.

Objectives: To assess feasibility of a future randomised controlled trial (RCT) of clinical and cost-effectiveness of lifestyle information and commercial weight management groups to support postnatal weight management to 12 months post-birth.

Design: Two-arm feasibility trial, with nested mixed-methods process evaluation.

Setting: Inner-city unit, south England.

Population: Women with body mass indices (BMIs) ≥25 kg/m at pregnancy booking or normal BMIs (18.5-24.9 kg/m ) identified with excessive gestational weight gain at 36 weeks of gestation.

Methods: Randomised to standard care plus commercial weight management sessions commencing 8-16 weeks postnatally or standard care only.

Main Outcomes: Feasibility outcomes included assessment of recruitment, retention, acceptability and economic data collation. Primary and secondary end points included difference between groups in weight 12 months postnatally compared with booking (proposed primary outcome for a future trial), diet, physical activity, smoking, alcohol, mental health, infant feeding, NHS resource use.

Results: In all, 193 women were randomised: 98 intervention and 95 control; only four women had excessive gestational weight gain. A slightly greater weight change was found among intervention women at 12 months, with greatest benefit. Among women attending ten or more weight management sessions. There was >80% follow up to 12 months, low risk of contamination and no group differences in trial completion.

Conclusion: It was feasible to recruit and retain women with BMIs ≥25 kg/m to an intervention to support postnatal weight management; identification of excessive gestational weight gain requires consideration. Economic modelling could inform out-of-trial costs and benefits in a future trial. A definitive trial is an important next step.

Tweetable Abstract: A feasibility RCT of postnatal weight support showed women with BMIs ≥25 kg/m can be recruited and followed to 12 months postnatally.