Measuring maternal mortality: a systematic review of methods used to obtain estimates of the maternal mortality ratio (MMR) in low- and middle-income countries

Background: The new global target for maternal mortality ratio (MMR) is a ratio below 70 maternal deaths per 100 000 live births by 2030. We undertook a systematic review of methods used to measure MMR in low- and middle-income countries. Sources of data: Systematic review of the literature; 59 studies included. Areas of agreement: Civil registration (5 studies), census (5) and surveys (16), Reproductive Age Mortality Studies (RAMOS) (4) and the sisterhood methods (11) have been used to measure MMR in a variety of settings. Areas of controversy: Middle-income countries have used civil registration data for estimating MMR but it has been a challenge to obtain reliable data from low-income countries with many only using health facility data (18 studies). Growing points and areas for further research: Based on the strengths and feasibility of application, RAMOS may provide reliable and contemporaneous estimates of MMR while civil registration systems are being introduced. It will be important to build capacity for this and ensure implementation research to understand what works where and how.