Compounding, not adding: a layered framework for why maternal health programs gain coverage without saving lives.

For 30 years, investment in maternal health has delivered rising coverage: more antenatal visits, more skilled attendance, and more births inside facilities. However, survival has not kept pace. Each of the two frameworks that dominate the field explains one half of this issue. The Three Delays Model identifies where along the path to care a woman dies; the social determinants tradition explains why those delays fall where they do. There is no framework that connects the two. This Perspective sets out a framework that does, which I call the Compounding Vulnerability Framework. It is conceptualized as a pyramid: a broad base of structural root causes (poverty, gender inequality, schooling, and geography), a band of social and economic barriers above it, and the three care-seeking delays stacked higher still, narrowing to the apex where a preventable death occurs. The organizing idea is that these disadvantages multiply rather than add. A program that works on one layer alone-particularly the middle and upper layers that throw off visible coverage figures-will raise those figures and leave mortality almost unchanged, because the obstacle simply moves to the next layer left untouched. Read against the documented record of national programs, the evidence is consistent with this expectation. The framework turns the familiar argument about what works into a question about how many layers an investment reaches at once.