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Int J Epidemiol. 1996 Oct;25(5):1017-22.

Applying the sisterhood method for estimating maternal mortality to a health facility-based sample: a comparison with results from a household-based sample.

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Centers for Disease Control and Prevention, Division of Reproductive Health, Atlanta, GA 30333, USA.



The sisterhood method is an indirect technique used to estimate maternal mortality in developing countries, where maternal deaths are often poorly registered in official statistics. It has been used successfully in many community-based household surveys. Because such surveys can be costly, this study investigated the suitability of using data collected in outpatient health facilities.


Adults visiting any one of 91 health centres or posts in a rural region of Nicaragua were randomly sampled and interviewed by health personnel. A sample size, proportional to the population served, was assigned to each facility and 9232 adults were interviewed. Characteristics of health facility users were compared with the general population to identify factors that would allow generalization of results to other settings.


Based on these data, the lifetime risk of maternal death was 0.0144 (1 in 69). This estimate is essentially identical to that from a household-based survey in the same region 8 months earlier, which obtained a lifetime risk of 0.0145 (1 in 69). These findings correspond to a maternal mortality ratio of 241 and 243/100000 livebirths, respectively.


This is the first report comparing results of the sisterhood method from household and health facility-based samples. The sisterhood method provided a robust estimate of the magnitude of maternal mortality. Results from the opportunistic health facility-based sample were virtually identical to results from the household-based study. Guidelines need to be developed for applying this low-cost and efficient aproach to estimating maternal mortality in suitable opportunistic settings at subnational levels.


Researchers compared maternal mortality estimates using the sisterhood method in a household survey conducted in November 1991 and in an outpatient health facility survey conducted in July 1992. Both surveys were conducted in Region I, a predominantly rural, mountainous area in northern Nicaragua. They analyzed data from 9232 interviews with adults younger than 49. The estimated lifetime risk of maternal death and the corresponding maternal mortality ratio were essentially identical for both the household and health facility surveys (0.145 and 0.144 [i.e., 1 in 69 of reproductive age died due to pregnancy-related events] and 243 and 241/100,000 live births, respectively). The estimates were similar for both surveys, even when the results were standardized for age, residence, and socioeconomic characteristics. An important limitation to the sisterhood method of estimating maternal mortality is that it estimates maternal mortality for a period about 10-12 years before the study and therefore cannot be used to assess the immediate effect of interventions to reduce maternal mortality. Nevertheless, in areas with poor maternal mortality surveillance or where no alternative exists to collecting population-based data, the sisterhood method can reliably estimate maternal mortality. These findings suggest that health facilities-based studies using the sisterhood method is a feasible, low-cost, and efficient method to estimate maternal mortality in certain settings at subnational levels.

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