Individual interventions, collective lessons: Developing mid-range theory on women's groups to improve health.

Background: Interventions with women's groups have been widely implemented to improve health outcomes in low- and middle-income settings, particularly India. While there is a large evidence base on the effectiveness of single interventions, it is challenging to predict whether a women's group intervention delivered in one setting can be expected to work in another. Methods: We applied realist principles to develop and refine a mid-range theory on the effectiveness of women's groups interventions, summarised key lessons for implementation, and reflected on the process. We synthesised primary data from several interventions in India, a systematic review, and an analysis of behaviour change techniques. We developed mid-range theories across three areas: maternal and newborn health, nutrition, and violence against women, as well as an overarching mid-range theory on how women's groups can improve health. Results: Our overarching mid-range theory suggested that effective interventions should: build group or community capabilities; focus on health outcomes relevant to group members; and approach health issues modifiable through women's individual or collective actions. We identified four key lessons for future interventions with women's groups, including the importance of skilled and remunerated facilitation, sufficient intensity, supply-side strengthening, and the need to adapt delivery during scale up while maintaining fidelity to intervention theory. Conclusions: Our experience demonstrated the feasibility of developing mid-range theory from a combination of evidence and insights from practice. It also underscored the importance of community engagement and ongoing research to 'thicken' mid-range theories to design effective and scalable women's groups interventions in India and similar settings.