Nigeria accounts for 28.3% of global maternal deaths, with a maternal mortality ratio of 1,047 per 100,000 live births, the highest nationally estimated figure globally. This study assessed reproductive health (RH) service preparedness across 143 primary health care (PHC) facilities in Edo State, Nigeria, constructed a validated nine-item RH Composite Preparedness Score (CPS), and identified structural determinants of preparedness deficits using multivariate regression. A census-based cross-sectional facility survey was conducted across all 18 Local Government Areas of Edo State (23–25 September 2020) using the SOML Integrated Supportive Supervision checklist, aligned with the WHO Service Availability and Readiness Assessment framework. Ordinary Least Squares and binary logistic regression were applied alongside chi-square and one-way ANOVA tests to examine geographic variation and structural predictors. The mean RH CPS was 4.92/9 (SD = 1.31), indicating that facilities lacked over half of essential RH items on average. Partograph availability was critically deficient at 17.5% and maternal death audit forms at 14.7%, representing gaps of 82.5% and 85.3% respectively. No significant inter-district variation was detected, indicating systemic rather than geographically localized failure. OLS regression was non-significant (R² = 0.031; p = .743), demonstrating that general infrastructure variables do not explain RH preparedness deficits. Among 14 secondary hospitals, partographs and maternal death audit forms were each absent in 57.1% of facilities. These findings indicate that RH preparedness failures are programmatically rather than infrastructure-determined, and are addressable through targeted procurement, competency-based training, and mandatory accountability mechanisms integrated into existing supervision systems.