<p>IDI participants by interview location and title.</p>

Caregivers were purposively selected based on engagement level with the intervention. Eighteen program staff and healthcare workers from three facilities in western Kenya participated in in-depth interviews. The Theoretical Domains Framework informed design of data collection tools.

Caregiver and healthcare worker perceptions of Family MUAC with two-way SMS centered on seven themes. The intervention was viewed as acceptable, cost-saving, appropriate, feasible, and empowering. Caregiver uptake was high, and integrating child growth monitoring with other health services may help enhance sustainability.

Barriers to uptake included inconsistent MUAC measurements, limited social support, and issues with phone sharing. Refresher trainings could increase accuracy of MUAC measurements and improve engagement. Direct communication with healthcare workers via SMS built trust and strengthened patient-provider relationships.

Caregivers also reported perceived cost savings, as SMS communication reduced unnecessary travel to health centers when children were not malnourished. This study supports Family MUAC with two-way SMS as a promising approach to empower caregivers and highlights their critical role in child health and nutrition interventions. Future interventions can focus on improving measurement accuracy and mitigating negative social influences on caregiver-led interventions.</p></div>