Key concepts

Maternal death: is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes.

Death in pregnancy, childbirth, and the puerperium: is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death (obstetric and non obstetric). The term "death in pregnancy, childbirth, and the puerperium” replaces the earlier term "pregnancy-related deaths".

Measures of maternal mortality

Maternal mortality ratio (MMR): the ratio of the number of maternal deaths during a given time period per 100,000 live births during the same time-period.

Maternal mortality rate (MMRate): the number of maternal deaths in a population divided by the number of women of reproductive age, usually expressed per 1,000 women.

Life time risk of maternal death: refers to the probability that a 15-year-old female will die eventually from a maternal cause if she experiences throughout her lifetime the risks of maternal death and the overall levels of fertility and mortality that are observed for a given population. The adult lifetime risk of maternal mortality can be derived using either the maternal mortality ratio(MMR), or the maternal mortality rate(MMRate).

Concepts related to maternal mortality measurement

PM: is the proportion maternal among deaths of females of reproductive age and is calculated as the number of maternal deaths divided by the total deaths among females aged 15–49 years.

Misclassification of maternal deaths: occurs when a maternal death is inaccurately classified to causes not used for the purpose of identifying maternal deaths (according to ICD-10 convention, maternal deaths are identified primarily using codes from Chapter 15) and/or where no indication of the temporal nature to pregnancy is indicated on the death certificate to flag this potential misclassification.

Underreporting of maternal deaths: may occur due to misclassification or if the death was never reported.

Definitions of variables used in the model to estimate maternal mortality

GDP per capita, PPP (constant 2005 international $): GDP per capita based on purchasing power parity (PPP). GDP in PPP is gross domestic product converted to international dollars using purchasing power parity rates. An international dollar has the same purchasing power over GDP as the U.S. dollar has in the United States. GDP at purchaser's prices is the sum of gross value added by all resident producers in the economy plus any product taxes and minus any subsidies not included in the value of the products. It is calculated without making deductions for depreciation of fabricated assets or for depletion and degradation of natural resources. Data are in constant 2005 international dollars. Data derived from The World Bank and Penn World Tables.

General fertility rate (GFR): is the number of live births per 1,000 women aged 15-49 in a given year. Data calculated from average births and female population over the PM or MMR time interval using data from the UN Population Division, 2010 revision.

Skilled attendant at birth (SAB): percentage of births attended by skilled health personnel (doctor, nurse or midwife). Data derived using all available data from national representative household surveys and other national sources (in databases maintained by UNICEF). Annual series were estimated by fitting a simple model of SAB as a function of time for each country.

Approaches to measuring maternal mortality

Vital registration (civil registration): this approach involves routine registration of births and deaths. Even where coverage is complete and the causes of all deaths are identified based on standard medical certificates, in the absence of active case-finding, maternal deaths may be missed or misclassified; and therefore confidential enquiries are used to identify the extent of misclassification and underreporting.

Household survey-based methods

• Direct reporting of all deaths occurring in the household: data on maternal deaths may be collected by direct reporting of deaths occurring in the household for some period (generally a year or two) preceding the interview. Limitations of this method include the following: the survey identifies all deaths in pregnancy, childbirth, and the puerperium (not only "maternal" deaths as defined above); and because maternal deaths are rare events in epidemiological terms, surveys to measure their levels require large sample sizes to provide statistically reliable estimates and therefore they are expensive.

• Sisterhood methods (direct): direct sisterhood methods obtain information by interviewing respondents about the survival of all their siblings (the age of all living siblings, age at death and year of death of those dead, and among sisters who died when at least 12 years of age, how many died during pregnancy, delivery, or within two months of the end of the pregnancy). This approach identifies all deaths in pregnancy, childbirth, and the puerperium, rather than maternal deaths. The direct sisterhood method generally produces estimates referring to a seven-year period preceding the survey, and these estimates are subject to substantial uncertainty (wide confidence intervals), making it difficult to monitor changes over time. This is the standard approach currently used in Demographic Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS).

• Sisterhood method (indirect): asks respondents four simple questions about how many of their sisters reached adulthood, how many have died and whether those who died were pregnant around the time of death. This method relies heavily on a number of assumptions about the relationships between fertility and age-specific maternal mortality. This approach is no longer commonly used, although before 2007 it was incorporated into some MICS surveys.

Census studies: a national census, with the addition of a limited number of questions, could produce estimates of maternal mortality; this approach eliminates sampling errors (because the entire population is covered) and hence allows a more detailed breakdown of the results, including time trends, geographic subdivisions, and social strata. This approach allows identification of deaths in the household in a relatively short reference period (1–2 years), thereby providing recent maternal mortality estimates, but is conducted at 10-year intervals and therefore limits monitoring of maternal mortality. The training of enumerators is crucial, since census activities collect information on a range of other topics which are unrelated to maternal deaths. Results must be adjusted for the completeness of births and deaths declared in the census, and for distortions in age structures, in order to arrive at reliable estimates.

Reproductive age mortality study (RAMOS): these are single, stand-alone studies, conducted over a specified time period with the objective to identify all deaths of reproductive aged women. The ideal starting point is complete listing of deaths of women of reproductive age, such as in complete vital registration systems. A key feature of the enquiry is triangulation among data sources (e.g. church records, burial grounds) to identify missed deaths. Each death is investigated to determine whether or not it was maternal, by detailed review of hospital, health facility case notes/records, and/or household interviews of family members. Studies may be done on a sampled basis, but should be a large enough sample to be representative of the entire population. It should also be noted that the results of these studies may be no better than the original listing of deaths and that in order to calculate MMR from inquiries/RAMOS studies, an accurate count of live births is also needed.

Verbal autopsy: this approach is used to assign cause of death through interviews with family or community members, where medical certification of cause of death is not available. The accuracy of the estimates depends on the extent of family members’ knowledge of the events leading to the death, the skill of the interviewers, and the competence of physicians who do the diagnosis and coding. The findings of verbal autopsy studies cannot be extrapolated to obtain national MMRs.