Background: HIV Sentinel Surveillance among pregnant women attending antenatal care clinics, ANC-HSS, is used to estimate HIV prevalence among the general population. Despite the declining trend, HIV prevalence among the general population in Karnataka is still higher than the national average (0.22%), with a recent, noticeable stabilization. Demographic analysis on concentrated HIV infection among pregnant women could be potential indicators for targeted HIV interventions among general population as well as and prevention of parent to child transmission (PPTCT). Objectives: To analyse the demographics of HIV-positive pregnant mothers in Karnataka, thereby identifying the most-at-risk populations (MARP) within the general population. Methods: In total, 24800 eligible pregnant women aged 15-49 attending the ANC clinic for the first time during the surveillance period (Jan-Mar, 2017) were enrolled. Demographic data and blood samples were collected, recorded and tested for HIV. Age-specific factors associated with HIV prevalence, besides the demographics of the HIV positive pregnant women, were analysed to identify the MARP for targeted HIV interventions. Results: Comprehensively, none of the demographic factors was significantly associated with HIV prevalence. Nevertheless, analysis of demographics, HIV test history and ART status of HIV-positive pregnant women reveals prominent prevalence patterns. The epidemic was majorly confined within young, less educated, primigravida and rural mothers of low economic status. Conclusion: ANC-HSS is designed to estimate the HIV prevalence among general population at national, state and district levels and is not reflective of the concentrated epidemic confined to MARP. Identifying the disease pattern specific to MARP is essential for effective targeted interventions and disease management.