Maternal healthcare utilization is crucial for reducing maternal mortality, yet remains low in many underserved regions. The CALCIUM intervention, a culturally tailored, digital platform-integrated intervention, was developed to promote antenatal care (ANC) and institutional deliveries in Liangshan Yi Autonomous Prefecture, an ethnic minority community in China. The CALCIUM intervention was developed to address barriers including limited healthcare awareness, traditional norms and low-quality services. This intervention will evaluate the effectiveness, and cost-effectiveness of improving maternal healthcare utilization and pregnancy outcomes in an ethnic minority community.