OBJECTIVE: We introduce a new and untested approach for the measurement of life-threatening maternal morbidity in populations where not all women give birth in a health facility. By defining complications at the very extreme end of the severity spectrum, we postulate that its count in hospitals can be used to represent the incidence in the general population. DESIGN: We counted all cases of life-threatening obstetric morbidity in hospitals and all maternal deaths in the population. Using these data, we describe the incidence of life-threatening morbidity in the total population, examine its variation across geographical areas and investigate its relationship with maternal mortality. SETTING: Serang and Pandeglang district in West Java, Indonesia. POPULATION OR SAMPLE: All women residing in the two districts. METHODS: Cross-sectional study of maternal morbidity and mortality. MAIN OUTCOME MEASURES: Pregnancy-related illness and mortality (PRIAM), consisting of life-threatening maternal morbidity (defined using the concepts of near miss and met need for life-saving surgery) and maternal mortality. RESULTS: The incidence of maternal mortality and life-threatening complications at the population level was 421 and 1416 per 100,000 births, respectively, resulting in an overall ratio of PRIAM of 1837 per 100,000. The overall incidence of PRIAM was much lower in rural than in urban areas (1529 and 2880 per 100,000, respectively, P < 0.001), and it was lowest in rural Serang (1304 per 100,000). CONCLUSIONS: The approach tested in this study--relying on conditions that are 'absolutely' life-threatening such that their count in hospitals can be used to represent the incidence in the general population--is promising but needs further testing in populations with varied disease epidemiology and access to care. Continued investments in hospital-based audits of life-threatening morbidity may ultimately improve the quality and reliability of information on obstetric complications and facilitate the development of rigorous and standard criteria for the definition of life-threatening morbidity.