Public sentiment on social media can shift rapidly during public health emergencies, yet phase-resolved evidence remains limited when essential maternal and reproductive health service access becomes the focal concern. Using an information ecology framework and a hybrid phase-resolved design, we analyzed 8,762 publicly accessible Sina Weibo posts and comments related to the widely reported Xi’an incident during COVID-19 control measures. The trajectory was summarized as a four-stage reporting structure: a one-day Emergency stage marking burst onset and the earliest intervention window, followed by Outbreak, Cooling, and Out-of-Focus stages whose later boundaries were checked with structural-break analyses of daily posting volume. Discourse shifted from rapid amplification and accountability framing near the attention peak to implementation-oriented discussion of service continuity, triage, and preparedness. Negative sentiment was most visible early, then declined and stabilized; this stabilization co-occurred more consistently with concrete access arrangements, such as hotlines and green-channel pathways, than with statements alone. Recurring rights- and access-oriented appeals highlighted frictions in obtaining essential care under restrictive measures. We interpret these findings as case-specific descriptive signals from one event on one platform that may complement formal monitoring of essential service continuity and emergency risk communication.