Data inputs for BKMR.

Background
Globally, maternal mortality is off track in achieving the Sustainable Development Goals by 2030. Over the past two decades, China has dramatically reduced maternal mortality in more developed (eastern) and less developed (western) regions. An understanding of the social and health system factors associated with maternal mortality in China may be helpful for countries attempting to meet the 2030 targets and beyond.
Methods and findings
We analyzed provincial-level data on maternal mortality and social and health system factors from the National Health Statistics Yearbooks and China Statistical Yearbooks from 2004 to 2020. We investigated the factors associated with maternal mortality before and after 2013, the year that a historic national program, Reducing Maternal Mortality and Eliminating Neonatal Tetanus, came to an end. Bayesian kernel machine regression was employed to analyze social and health system factors (urbanization rate, per capita disposable income, average years of schooling, number of health technical personnel in maternal and child healthcare, number of hospital beds for obstetrics and gynecology, local fiscal expenditure on healthcare, prenatal booking rate, antenatal care rate, and hospital delivery rate) as a mixture and identify the factors with larger posterior inclusion probability and a higher value of the exposure–response relationship for the total and cause-specific maternal mortality. In the East, an increase in hospital delivery rate correlated with the decrease in total maternal mortality [posterior mean and standard deviation (SD): −14.8(1.5)] before 2013, and the urbanization rate was negatively associated with total maternal mortality [posterior mean and SD: −3.9(0.6)] after 2013. Hospital delivery, urbanization, local fiscal expenditure on healthcare, and antenatal care were the factors associated with reduced cause-specific maternal mortality in the East. In the West, an increase in antenatal care rate was associated with reduced total maternal mortality, with the posterior mean and SD of −33.8(6.8) and −11.5(4.1) before and after 2013, respectively. Hospital delivery and antenatal care were the factors associated with reduced cause-specific maternal mortality in the West. The main limitation of this study was the data constraints in the national statistics.
Conclusions
Coverage of maternal care, health financing, and urbanization were the factors associated with the substantial reduction in maternal deaths in Eastern and Western China during 2004–2020. The improvement of the quantity and quality of antenatal care and hospital delivery may be a viable policy priority in less developed regions worldwide.