Indicator 13: Institutional maternal mortality ratio

Determining how many maternal deaths occur in the health system and tracking changes over time is an important way to gauge whether the health system’s strategies and programming are having the desired impact: a reduction in maternal mortality.

The WHO defines a maternal death as: “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from unintentional or incidental causes.”¹

Maternal deaths can be from either direct or indirect causes. Maternal deaths from direct obstetric causes are those “resulting from obstetric complications of the pregnant state (pregnancy, labour and puerperium), and from interventions, omissions, incorrect treatment, or from a chain of events resulting from any of the above.” Direct obstetric causes of death include: antepartum and postpartum hemorrhage (including retained placenta), severe pre-eclampsia and eclampsia, postpartum sepsis, severe abortion complications, uterine rupture, prolonged/obstructed labor and ectopic pregnancy. Deaths that result from complications of anesthesia or cesarean section are also considered to be from direct obstetric causes.² Maternal deaths from indirect causes are those deaths that result “from previous existing disease or disease that developed during pregnancy, and that were not due to direct obstetric causes but were aggravated by the physiologic effects of pregnancy.” Indirect obstetric causes of death include: existing cardiac or renal disease, or infectious diseases such as HIV, TB, and malaria.³⁴

Maternal deaths occur either inside or outside the health system. This indicator, like Indicator 14: Direct obstetric case fatality rate, focuses on maternal deaths that occur in health facilities. The IMMR therefore differs from the population-based maternal mortality ratio (MMR) because the population-based MMR includes all maternal deaths, regardless of where they occur. In countries where nearly all women give birth in facilities and maternal death data are good quality, the IMMR gives a good approximation of the overall population-based MMR.

The numerator includes all maternal deaths from direct, indirect and unspecified causes that occur in health facilities. The denominator is the number of live births in the same set of health facilities during the same time period. The indicator is typically expressed per 100,000 live births.

The numerator and denominator come from the same set of facilities.

Data on maternal deaths are ideally captured by the civil registration and vital statistics (CRVS) system in a country. However, few low-and middle-income countries have CRVS systems that produce high-quality cause of death data.⁵ Therefore, data for this indicator most often come from the HMIS and originate from health facility registers in a range of locations: the maternity unit, the operating theater, the inpatient women’s unit, other relevant wards and the morgue. Data on maternal deaths can also be captured from maternal death reviews and other types of clinical audits.

While this indicator is typically calculated at the national level, it is possible to calculate this indicator at the sub-national level if all facilities in the sub-national area are included.

Even if data on maternal deaths and live births are collected routinely in the HMIS, the IMMR is most usefully calculated and analyzed on an annual basis.

It is important to look at changes in the IMMR over time. When the IMMR goes down, it is important to look at the other EmONC indicators to learn what aspects of care have improved: are most EmONC facilities offering services under optimal conditions and functioning well? Are women and health providers having positive experiences and are services appropriate and high quality? If the IMMR is stagnant or has gone up, looking at the other EmONC indicators can give a sense of what else may be happening in the health system: Have there been systemwide shortages of key medications or supplies? Are facilities facing severe shortages of competent staff? Is IMMR being measured only in public facilities and women who deliver in private-sector facilities and have severe obstetric complications are dumped in public facilities where they die? (“Dumping” is when one facility takes a critically ill woman to another facility in order to keep casualties low at the first facility.)

The IMMR is best analyzed and interpreted at the sub-national and national levels. For individual facility level monitoring of maternal mortality, please refer to Indicator 14: Direct obstetric case fatality rate.

When presenting the IMMR, it is important to be clear that it is different from the population-based maternal mortality ratio (i.e., from Demographic and Health Surveys, WHO global estimates) and they should not be used interchangeably when tracking progress over time.

Analyze the distribution of causes of institutional maternal deaths:

Examining the distribution of causes of maternal death allows planners to focus strategies, resources and implementation on addressing the leading causes of death. By analyzing maternal deaths in this way, it is also possible to learn what proportion of maternal deaths are due to direct obstetric causes (e.g., postpartum hemorrhage, eclampsia, sepsis) versus indirect causes (e.g., malaria, HIV/AIDS, tuberculosis, pre-existing cardiovascular disease, diabetes, severe anemia).

To calculate this indicator, the number of maternal deaths separated by cause (see Groups of underlying causes of death during pregnancy, childbirth and the puerperium to help standardize the causes) are divided by the total number of maternal deaths from all causes (i.e., direct, indirect and unspecified) that occur in the same set of health facilities during the same time period. Data source(s) for calculating this indicator are discussed above in ‘Data Sources.’

When analyzing and interpreting the distribution of causes of maternal deaths, it is first useful to see what proportion of maternal deaths are due to direct obstetric and indirect obstetric causes. If the proportion of deaths due to indirect causes is increasing, interventions beyond EmONC may be needed. Another useful way to look at the data is to look at the specific causes of death for both direct and indirect causes. Causes that account for a high proportion of maternal deaths may be good candidates for quality improvement interventions focused on prevention, identification, and management of those complications. It is also important to look at the number of maternal deaths that are recorded as ‘unknown / unspecified causes’ as this indicates a need to improve recording of data.

Pie charts (or bar charts) can effectively present the part-to-whole relationship of causes of institutional maternal deaths.

• Monitor Indicator Sheet – Maternal Mortality Ratio: https://monitor.srhr.org/#home
• Verbal autopsy - https://www.who.int/standards/classifications/other-classifications/verbal-autopsy-standards-ascertaining-and-attributing-causes-of-death-tool
• Maternal and Perinatal Death Surveillance and Response (MPDSR): https://www.who.int/publications/i/item/9789240036666