Cluster randomised controlled trial of a household-level, group preconception nutrition awareness and norm intervention (SUMADHUR) combined with multiple micronutrient supplements (MMS) for newly married households: a protocol.

Introduction: Micronutrient deficiencies remain prominent drivers of adverse maternal and child health outcomes in Nepal. Gender-based inequalities and norms around women's status and access to nutrition exacerbate poor nutritional status. Many newly married, preconception women lack adequate nutrition due to delayed engagement with the health system and limited autonomy to prioritise their own health. To address this gap, the Sumadhur trial provides multiple micronutrient supplements (MMS) alongside a household-level behavioural intervention targeting newly married women, their husbands and mothers-in-law.

Methods And Analysis: This will be a village-cluster randomised controlled trial across three districts in Nepal, enrolling 700 households, each comprising a triad of newly married woman, husband and mother-in-law. Villages will be randomised to receive either Sumadhur behavioural intervention+MMS (intervention) or standard of care (control). In intervention villages, participants will join weekly group sessions for 5 months, covering maternal and reproductive health, equitable household food allocation and nutrition information, and gender norms and household relationships. Women will receive three bottles of MMS (180 tablets each) over 18 months. Quantitative data collection at baseline, 6, 12 and 18 months will include surveys, venous blood draws (not at 12 months) and anthropometry. Primary outcomes will be anaemia prevalence and micronutrient status (iron, folate, vitamin B). Secondary outcomes will include reproductive behaviours, birth outcomes and intrahousehold relationship dynamics. A nested qualitative component will employ longitudinal in-depth interviews with triads to understand the mechanisms of behavioural change. Impact will be measured through an intention-to-treat approach using mixed-effects logistic regression analyses.

Ethics And Dissemination: The study is approved by institutional review boards in the Ethics Board of the Nepal Health Research Council and the University of California, San Francisco IRB. Results will be disseminated to participating communities, local stakeholders and international audiences through workshops, peer-reviewed publications and policy briefs.All data will be made publicly available (deidentified) after the publication of the main impact paper.

Trial Registration Number: NCT06810440.