Maternal mortality remains a critical public health challenge in sub-Saharan Africa. While investments in facility infrastructure are common, rigorous evidence on the causal impact of holistic facility systems—encompassing management, supply chains, and clinical protocols—on patient outcomes is limited. This study aimed to quantify the causal effect of a comprehensive maternal care facility systems intervention on key clinical outcomes in a sub-Saharan African setting. We employed a quasi-experimental difference-in-differences design using longitudinal patient-level data from a nationally representative sample of facilities. The primary model was specified as $Y_{it} = \beta_0 + \beta_1 (\text{Treat}_i \times \text{Post}_t) + \gamma_i + \delta_t + \epsilon_{it}$, where $Y_{it}$ is the clinical outcome for facility $i$ at time $t$. Inference was based on cluster-robust standard errors. The intervention significantly reduced the incidence of postpartum haemorrhage by 7.3 percentage points (95% CI: -10.1, -4.5). No statistically significant effects were observed for other primary outcomes, including neonatal sepsis. Strengthening integrated facility systems can directly improve specific, process-sensitive maternal clinical outcomes, but may not uniformly affect all endpoints. Policy should prioritise integrated systems strengthening with targeted clinical training, particularly for haemorrhage management. Future programmes require embedded, rigorous evaluation to identify mechanisms of impact. maternal health, health systems, difference-in-differences, quasi-experimental, Ghana, clinical outcomes This study provides novel causal evidence on the effect of a multifaceted facility systems intervention on hard clinical endpoints, moving beyond input or output measures common in health systems research.