The study analyzed social and health system factors associated with maternal mortality in eastern and western China from 2004–2020. In the East, increases in hospital birth rates were correlated with decreases in total maternal mortality (posterior mean and SD: −14.8 (1.5)) before 2013. After 2013, urbanization rates were negatively associated with total maternal mortality (posterior mean and SD: −3.9 (0.6)). In the West, increases in antenatal care rates were associated with reduced total maternal mortality (posterior mean and SD: −33.8 (6.8) before 2013 and −11.5 (4.1) after). Hospital delivery and antenatal care were factors associated with reduced cause-specific maternal mortality in the West. Local health care expenditures were associated with urbanization and reduced maternal mortality in the East. The main findings show that maternal care coverage, health financing and urbanization significantly affect maternal mortality. Improving the quantity and quality of prenatal and hospital care can be an effective policy strategy in less developed regions.