Maternal mortality ratio
The annual number of female deaths from any cause related to or aggravated by pregnancy or its management (excluding accidental or incidental causes) during pregnancy and childbirth or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, expressed per 100 000 live births, for a specified time period (1,2,3).
Maternal deaths include the death of a woman during pregnancy, childbirth, or within 42 days of termination of pregnancy from any cause related to the pregnancy or its management, excluding deaths due to accidental or incidental causes (4).
There are three common data sources for this indicator:
- Civil registration and vital statistics (CRVS) and other routine national surveillance systems
- Routinely collected administrative data
- Population-based household surveys.
Civil registration and vital statistics systems:
A well-functioning and integrated national or subnational CRVS system will universally register and certify vital events, including live births, stillbirths and deaths that occur in the country or administrative area. Birth and death certificates should be issued as part of the CRVS system, allowing the compilation, analysis and dissemination of information through vital statistics agencies, including population characteristics (e.g. sex, date of birth or death, place of birth or death, place of usual residence) and cause-of-death information. Some CRVS systems will also register and certify other important vital events within the population, such as adoptions, marriages and divorces (5).
Data from CRVS are the preferred data source for this indicator when the system freely and universally records vital events, issues medical certification of cause of death, and the data are recorded in a systematic manner that ensures high data quality for both the public and private health sector and regardless of location of death (e.g. health facility or community-based births and deaths).
Key source of data: The main source of data from this indicator involves several steps and varies based on the policies and procedures of the national or subnational CRVS or other routine system within health facilities and/or within communities. Declaration of maternal death events are obtained through:
(a) forms completed by health personnel at health facilities; or
(b) community-based sources, including death registration forms.
Either paper or electronic forms containing this information are then submitted to the relevant civil authorities or vital statistics agencies, which have the responsibility to officially record the maternal death and characteristics, such as name, date and place of birth, nationality, place of death and cause of death. At the national or subnational level, the civil authority or vital statistics agency issues death certificates. The use of standardized definitions using the ICD-MM is important for consistent case ascertainment and cause-of-death information (6). Moreover, inclusion of indication that the death occurred during pregnancy or within 42 days after the termination of pregnancy or childbirth on death certificates is critical. National or subnational civil authorities or vital statistics agencies are responsible for reporting of this indicator.
Indicator definition and calculation: The indicator is calculated as the number of deaths from any cause related to or aggravated by pregnancy or its management (excluding accidental or incidental causes) during pregnancy and childbirth or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, expressed per 100 000 live births, for a specified time period.
The calculation is as follows:
(Number of maternal deaths during a specified time period / Total number of live births during a specified time period) x 100
To compute the rate per 100 0000 live births, the numerator is divided by the denominator and multiplied by 100 000. The numerator requires information on pregnancy status, timing of death (during pregnancy, childbirth, or within 42 days of termination of pregnancy), and information about the cause of death (3). The denominator should include only live births.
Frequency of measurement: Within CRVS, this indicator is generally monitored at a national or subnational level on an annual basis. As a guide, the recommended frequency of measurement based on reporting level is outlined below:
- National and subnational level: Annually (data can be aggregated subnationally to provide national-level data).
Disaggregation: By age, place of residence (e.g. urban, rural), socioeconomic status (e.g. education level, wealth quintile), timing of death, place of death, type of death (e.g. direct or indirect obstetric death), cause of death and type of reporting source (e.g. health facility, community).
Missing values: Maternal deaths are often under-reported, and misclassified and missing values are handled through model estimation and/or projection of trends where data are limited (7). Depending on capture of cause-of-death information on the medical death certificates, linkages to other data sources (e.g., administrative data) may need to be done and timing and cause-of-death
information can be abstracted from medical chart reviews.
Routinely collected administrative data:
Data from routinely collected and compiled administrative data sources will provide information as recorded in medical charts/records or registers and are entered into national and/or subnational health information systems:
- Health information management system (HMIS) and/or
- District Health Information Management System (DHIS2).
Data from health information systems may collect information on the number of women who died from a cause related to or aggravated by pregnancy or its management. Routinely collected administrative data and health facility statistics are the preferred data source in settings where the CRVS is non-functioning and there is a high utilization of health facility services and data are recorded in a manner that ensures good data quality for both the public and private health sectors. However, cause of death may or may not be available in administrative data sources, so linkages with other data sources and medical chart review and data abstraction may need to be done to identify cause-of-death information.
Key source of data: Administrative data sources include health facility and health services data abstracted from obstetric and medical records. Relevant information is recorded by health personnel within health facilities on paper forms completed by health personnel and/or through an electronic medical record. Data from paper or electronic sources are entered or abstracted into a database or registry and are compiled and analyzed within the national and/or subnational HMIS. The ministry of health (MoH) and/or national statistical offices (NSO) are usually responsible for the reporting of this indicator.
Indicator definition and calculation: The indicator is calculated as the number of deaths in health facilities from any cause related to or aggravated by pregnancy or its management (excluding accidental or incidental causes) during pregnancy and childbirth, or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, expressed per 100 000 live births in health facilities, for a specified time period.
The calculation is as follows:
(Number of maternal deaths in a health facility during a specified time period / Total number of live births in a health facility during a specified time period)
To compute the rate per 100,000 live births, the numerator is divided by the denominator and multiplied by 100,000. The numerator requires information on number of maternal death (3). The denominator should include only live births.
Frequency of measurement: The indicator can be calculated on an annual basis or a more aggregated basis (5- to 10-year time period), depending on number of deaths (sample size may be small) and facility, subnational and national processes for data entry, compilation and analysis. For internal purposes, MMR may be tracked on a more frequent and ongoing basis (e.g., quarterly) at the health facility level, if needed. As a guide, the recommended frequency of measurement based on reporting level is outlined below:
- Facility level: Quarterly or annually, or as needed based on the
country and/or facility need
- Subnational (first and second administrative) level: Annually
- National level: Annually (data can be aggregated to provide national-level data).
Disaggregation: By age, place of residence (e.g. urban, rural), socioeconomic status (e.g. education level, wealth quintile), timing of death, place of death, level of facility and location of facility (e.g., urban, rural).
Missing values: Maternal deaths are often under-reported and/or misclassified. Where data are limited, misclassified and/or under-reported, correction factors are applied when developing model-based global comparable estimates (7). Depending on capture of cause-of-death information in the HMIS, more accurate cause-of-death information can be abstracted from medical chart reviews.
Population-based household surveys:
Population-based household survey data or censuses are the preferred data source where there is a non-functional CRVS, HMIS, or other administrative data system, in settings with a low utilization of health facility services or where private health sector data are excluded from routinely collected administrative data. In the absence of complete death registration, information on maternal mortality can be collected through population-based household surveys collected through nationally or subnationally representative and statistically sound questionnaires, such as:
- Demographic Health Surveys (DHS) (8)
- Multiple Indicator Cluster Surveys (MICS) (9)
- Reproductive Age Mortality Studies (RAMOS)
- Other household surveys with a similar methodological design.
Key source of data: Depending on survey methodology, a household questionnaire is used to collect information on characteristics of the usual residents and visitors who slept in the household the night before the interview, as well as to identify members of the household eligible for an individual interview, such as women and men of reproductive age and children under the age of 5 years old.
Maternal mortality can be estimated using a few different approaches (10). The first approach is by obtaining information on all deaths of any member in the household. The household survey is designed to collect information on household recent deaths within the past 12 months, or other defined reference period, including the name, sex, age at death and reported cause of death. If the household member was a woman of reproductive age, the timing of death relative to pregnancy, childbirth, or the postpartum period is also elicited (e.g., household members are asked if the death occurred (a) while pregnant; (b) during childbirth; or (c) within two months of the end of a pregnancy).
Another approach is the sibling or sisterhood method, whereby information is obtained on a full sibling history through individual interviews with eligible women (aged 15–49) who are residents of the household. The information collected for each sibling (all siblings born to the woman’s natural mother) includes: name; sex (male, female); whether still alive (yes, no); if still alive, age in years; and if dead, number of years that have elapsed since the sibling died, and age at death. If the sibling who died was the eligible woman’s sister (female) above the age of 12 years old at the time of death, separate questions are asked to identify if the sister died either (a) while pregnant; (b) during childbirth; or (c) within two months after the end of pregnancy or childbirth. If the death was reported to have occurred after pregnancy or childbirth, the woman is asked the number of days after the end of pregnancy or childbirth when the sister died. To ascertain whether or not the death was directly related to pregnancy or childbirth, further questions are asked to determine if the death was either due to an act of violence or due to an accident.
The RAMOS survey uses various data sources (e.g., interviews with family members, CRVS, health-care facility records, burial records, traditional birth attendants), depending on the context, to identify all deaths of women of reproductive age and to ascertain which of these deaths are maternal or pregnancy related (3).
The MoH and NSO typically conduct household surveys and compile, analyze and report the results for this indicator in collaboration with the survey program (e.g. DHS, MICS, RHS) and funding agency.
Indicator definition and calculation: Depending on survey design, individual women of reproductive age (15–49 years old) are asked about the living status of all of their sisters. The indicator is calculated during a specified reference period, which is typically seven years before the time of the survey completion. The definition is as follows: The percentage of interviewed women (aged 15–49 years) with sisters who died during pregnancy, childbirth, or within 42 days of termination of pregnancy during a specified time period prior to survey completion, typically 0–6 years or 7–13 years, is expressed per 100 000 births during a specified time period.
The indicator is calculated as follows:
(Number of interviewed women (aged 15–49 years) with sisters who died during pregnancy, childbirth, or within 42 days of termination of pregnancy during a specified time period prior to survey completion / Age-adjusted general fertility rate for the same time period prior to survey completion) (10)
To compute the rate per 100,000 births, the numerator is divided by the denominator and multiplied by 100,000. This indicator identifies pregnancy-related deaths, not maternal deaths, and cause-of-death information is not captured. Thus, the indicator represents the pregnancy-related MMR
Frequency of measurement: Household surveys are typically conducted every 3–5 years.
Disaggregation at population level: By age, place of residence (e.g., urban, rural), and socioeconomic status (e.g., household wealth quintile).
Missing values: Missing values for unknown sibling maternal status at the time of death are not included as maternal deaths. For missing number of days after the end of pregnancy or childbirth when the sibling died, it is assumed that the death occurred within the first two months (or 42 days for global comparison). Missing values for whether or not the death occurred as the result of an act of violence or due to an accident are assumed to have not been due to an accident.
An estimated 295,000 (uncertainty interval 80%: 279,000 to 340,000) women died from pregnancy or childbirth-related complications in 2017 (7). Although progress has been made since 1990 (4), preventable pregnancy and childbirth complications are among the leading causes of maternal mortality, morbidity and disability among women of reproductive age in low- and middle-income countries, and disproportionately affect the most vulnerable women (4). An analysis conducted by the World Health Organization (WHO) found that haemorrhage, hypertensive disorders and sepsis were the three leading direct causes of maternal death, all of which could be preventable with appropriate and timely access to health services (11).
The MMR is an indicator of a nation’s health status and is a key performance indicator that is monitored and tracked globally as a measure of the health system’s functioning. Universal, accurate and timely measurement of the MMR, regardless of the location of death (e.g. community or health facility), with cause-of-death information is important to facilitate health systems planning and provision of health services delivery (12). Maternal cause-of-death indicators help program management at global, national and subnational levels by monitoring and evaluating whether safe motherhood and maternal and newborn health programs are on target for reducing maternal mortality, and more broadly, for strengthening health systems. Accurate ascertainment and review of maternal deaths facilitates the identification and recommendations for opportunities for quality improvement and prevention in order to eliminate all future preventable maternal deaths from occurring (4).
Maternal deaths, measured through a CRVS system, are also a measure of a country’s capacity to plan and implement an effective civil registration system or vital statistics agency that is able to accurately and systematically report maternal deaths and implement ongoing surveillance and response. The quality of reporting of this indicator varies greatly between and within countries, particularly in countries without effective civil registration systems in place; adjustment factors for more accurate measurement are done by WHO for global comparability (7). Comparisons of the MMR at the national or subnational level over time can be used to identify areas where improvements in health system functioning are needed and areas for improved contact with the health system are needed to provided adequate, timely and quality care for women during pregnancy, childbirth and postpartum.
Civil registration and vital statistics systems:
Death registration for all maternal deaths that includes cause-of-death information should be part of a national and/or subnational CRVS system. However, CRVS systems are either non-existent and/or the complete coverage, accuracy and timeliness of civil registration systems is a major issue in many countries worldwide. In order to assess the completeness of the CRVS system, evaluations should be conducted to ascertain the quality of the system, as recommended by the United Nation’s revised Principles and Recommendations for a Vital Statistics System (5).
As a result, it is common for deaths to be unregistered or for death certificates to not include information on whether or not the death occurred during pregnancy, childbirth, or within 42 days after termination of pregnancy or childbirth. This may be due to lack of a legal framework within civil authorities or vital statistics agencies or a functioning CRVS system, especially when it comes to deaths that occur at home or in the community as opposed to a health facility. Even in countries with functional CRVS systems and legal frameworks in place, missing or unregistered deaths still occur due to health professionals and/or family members not knowing about the requirement to register deaths. As a result, many CRVS systems under-report the majority of maternal deaths due to lack of capturing information on whether or not the woman was currently or recently pregnant. Often, linkages to other data sources, such as administrative data, are required in order to identify more accurate estimates of the MMR.
Data collected from administrative and other routine data systems:
Administrative data may suffer from poor quality such as irregularities in report generation, data duplication and inconsistencies (12). Reporting challenges exist at the facility level given data quality issues, including incomplete, inaccurate and lack of timely data due to insufficient capacity in the health system or inadequate system design, such as no integration with the private sector.
Many HMIS databases or registries are event-based and only include women who died in a health facility during delivery. Some administrative systems may capture information on deaths that occur in health facility settings for deaths that occur during transfers of care or admissions/re-admissions within the 42 days postpartum. However, cause-of-death information may be lacking in these instances.
Data collected through household surveys:
The systematic recording of deaths in many countries remains a serious challenge. In the absence of reliable CRVS systems or administrative data, household surveys have become the key source of data to monitor levels and trends of maternal mortality. In most low-and middle-income countries, such surveys represent the sole source of this information.
In population-based household surveys, eligible women are asked about the pregnancy status of sisters of reproductive age and whether or not the woman died during pregnancy, childbirth, or two months after pregnancy or childbirth; however, maternal cause-of-death information is not asked in the current iterations of the MICS or DHS questionnaires, which compromises the ability to measure the “cause of maternal death” indicator and instead allows for measurement of pregnancy-related mortality ratio.
Respondents to the survey may not always understand that the surveyors are interested in collecting information on household members or siblings who are no longer alive. Additionally, many respondents will not report on deaths of household and family members due to cultural sensitivities.
The WHO Global Health Observatory maintains a database for global monitoring and reporting of maternal mortality. Before data can be included in the global databases, WHO undertakes a process of data verification that includes correspondence with field offices to clarify any questions regarding the reported statistics. More information about the WHO database on maternal mortality can be found at: https://www.who.int/gho/maternal_health/mortality/maternal/en/.
For more information on this indicator, see the MoNITOR indicator reference sheet developed by WHO: Who-indicators (srhr.org).
safe motherhood (SM)
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