BACKGROUND:
Antenatal care (ANC) and childhood immunization are central components of the maternal and child health continuum, yet their linkages within routine health systems remain insufficiently documented. Understanding how ANC performance aligns with immunization outcomes at facility level is essential for strengthening integrated service delivery in Rwanda.

METHODS:
We conducted a retrospective observational study using Rwanda’s national Health Management Information System (HMIS) data from 2017–2024. Eight ANC indicators and two immunization outcomes—DTP-HepB-Hib3 (DTP3) and Measles-Rubella second dose (MR2)—were extracted and merged by facility-year. Indicators with >30% missingness were excluded, leaving four ANC variables for the primary analysis. Descriptive statistics and Pearson correlation analyses were performed, alongside facility-level comparisons and time-series and lag analyses.

RESULTS:
The dataset included 1,271 health facilities nationwide. ANC new registrations showed substantial variation across facilities (mean 438; SD 585), as did immunization outputs (DTP3 mean 406; MR2 mean 380). All ANC indicators demonstrated strong positive correlations with DTP3 and MR2 (all p < 0.001). The highest correlations were observed for ANC new registrations (r = 0.804 for DTP3; r = 0.793 for MR2) and early ANC contact in the first trimester. Time-series analysis revealed close alignment of ANC and immunization trends. Lag analysis showed near-perfect same-year correlations (DTP3 r = 0.997; MR2 r = 0.993), moderate correlations at lag-1 (~0.82), and minimal associations at lag-2 (~0.39).

CONCLUSIONS:
ANC service utilization is strongly associated with childhood immunization outcomes in Rwanda’s routine health system. Early ANC engagement and high overall ANC volumes are particularly predictive of DTP3 and MR2 performance. These findings support the role of ANC as a critical entry point for strengthening the continuum of care and improving child health outcomes.