In Mexico, the measurement of maternal death has demonstrated the extent to which the risk to women's lives is determined by their class, location, and ethnicity. In this paper, I examine how the Mexican federal government has implemented measurement and monitoring regimes to track and respond to maternal deaths. Drawing on field research and interviews conducted at various times between 2004 and 2010, I consider some of the contradictory knowledge and governance effects that this turn to measurement has generated in the Mexican health-care system. Measurement and monitoring regimes, I argue, have given maternal health advocates the evidence to argue that it is failings within the health-care system which have made high levels of mortality so intractable. At the same time, measuring mortality has rendered broader aspects of sexual and reproductive rights less visible, while also generating a politics of responsibility and culpability. I trace in this paper a tendency by some health-care professionals to resist what they see as the punitive nature of maternal health monitoring regimes, by either 'gaming' the numbers, and/or shifting responsibility other, usually more vulnerable, populations. This analysis highlights the importance of attending to the context in which measurement regimes are introduced. In the context of a deeply flawed system, measurement regimes will generate tensions around responsibility which cannot easily be resolved, and may be resisted by those on whom the regime depends for its reliability.