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# Maternal mortality ratio

- Measure

It counts women who die from causes linked to pregnancy, birth or the weeks after, per 100,000 live births. Almost all these deaths are preventable.

Updated Nov 5, 2026

## Key points

- Maternal mortality ratio = maternal deaths / live births in the period × 100,000.
- Window: during pregnancy or up to 42 days after its end, whatever the duration or site of the pregnancy.
- Direct: from obstetric complications (haemorrhage, hypertensive disorders, infection, complications of abortion).
- Indirect: from a disease that was present before or arose in pregnancy and was aggravated by it (for example, heart disease).
- It is called a ratio because live births are not the population at risk (pregnant women); they are a practical stand-in.
- Late maternal deaths (42 days to one year) are counted separately.

On this page

- The basics Key points
- What it is
- Formula and reading
- Worked example
- Direct versus indirect deaths
- Markers
- How to read it
- Common pitfalls
- Memory aid

- Study Test yourself

- Connections Connections

## What it is

A maternal death is the death of a woman during pregnancy or within 42 days of its end, from any cause related to or aggravated by the pregnancy or its management; accidental or incidental causes are excluded. The maternal mortality ratio divides these deaths by the live births of the same period and multiplies by 100,000. It is a core indicator of the quality of obstetric care.

## Formula and reading

- MMR = (maternal deaths in the period / live births in the same period) × 100,000.
- Accidental or incidental deaths are excluded (for example, a road crash in a healthy pregnant woman).
- Late maternal death: from direct or indirect obstetric causes, more than 42 days but less than one year after the end of pregnancy.
- Because the events are few each year, the ratio of a small municipality swings widely: read averages over several years.

## Worked example

- A made-up department records 40,000 live births in a year and 31 deaths of pregnant or postpartum women.
- Exclude 3 from accidental causes and 2 that happened after 42 days (late deaths): 31 − 5 = 26 maternal deaths remain.
- MMR: 26 / 40,000 = 0.00065; × 100,000 = 65 maternal deaths per 100,000 live births.
- Of the 26, 18 are direct (8 from haemorrhage, 7 from hypertensive disorders and 3 from sepsis) and 8 are indirect.
- Share of direct deaths: 18 / 26 = 0.692, about 69% (rounded).
- Reading: most are direct obstetric deaths, prevented by antenatal care, skilled birth attendance and a fast response to haemorrhage.

## Direct versus indirect deaths

| Type | Cause | Examples |
| --- | --- | --- |
| Direct | Complications of pregnancy, birth or the puerperium, or of their management | Postpartum haemorrhage, pre-eclampsia and eclampsia, sepsis, complications of abortion |
| Indirect | A disease present before or arising in pregnancy and aggravated by it | Heart disease, infectious or metabolic diseases that worsen in pregnancy |
| Not counted | Accidental or incidental cause | Injury from a road crash or violence unrelated to the pregnancy |

## Markers

- MMR
- × 100,000 LB
- 42 days
- Direct
- Indirect

## How to read it

- In Colombia, maternal deaths are notified to SIVIGILA and the cases are studied in case-review units to find avoidable delays.
- The three questions of any case review: was there a delay in deciding to seek care, in reaching the service, or in receiving adequate care?

## Common pitfalls

- Calling it a rate and dividing by the female population: the correct denominator is live births.
- Counting accidental or late deaths in the main ratio.
- Concluding that a municipality got worse because it went from 1 to 2 deaths in a year: with small numbers, look at series of years.

## Memory aid

‘Forty-two days and a hundred thousand births’: the window and the multiplier of the maternal ratio.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the denominator of the maternal mortality ratio?

Live births in the same period; the result is given per 100,000 live births.

## Up to how many days after the end of pregnancy is a death counted as maternal?

Up to 42 days. Deaths after that, up to one year, are late maternal deaths and are counted separately.

## A healthy pregnant woman dies in a road crash. Does she enter the maternal mortality ratio?

No: accidental or incidental causes are excluded.

## With 12 maternal deaths and 30,000 live births, what is the ratio?

12 / 30,000 × 100,000 = 40 per 100,000 live births.

## What separates a direct maternal death from an indirect one?

A direct death results from obstetric complications; an indirect one from a pre-existing or intercurrent disease aggravated by pregnancy.

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## Connections

## Related 5

- [Infant, neonatal and perinatal mortality](https://durgical.com/en/epidemiology/infant-neonatal-and-perinatal-mortality/)
- [Mortality rates: crude and specific](https://durgical.com/en/epidemiology/mortality-rates-crude-and-specific/)
- [Notifiable events in Colombia](https://durgical.com/en/epidemiology/notifiable-events-in-colombia/)
- [SIVIGILA: public health surveillance in Colombia](https://durgical.com/en/epidemiology/sivigila-public-health-surveillance-in-colombia/)
- [Comprehensive health care pathways (RIAS)](https://durgical.com/en/epidemiology/comprehensive-health-care-pathways/)

## Related conditions 5

- [Postpartum haemorrhage](https://durgical.com/en/conditions/postpartum-haemorrhage/)
- [Preeclampsia](https://durgical.com/en/conditions/preeclampsia/)
- [Eclampsia](https://durgical.com/en/conditions/eclampsia/)
- [Ectopic pregnancy](https://durgical.com/en/conditions/ectopic-pregnancy/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)

[← All of epidemiology](https://durgical.com/en/epidemiology/)

Educational content on epidemiological and statistical methods; the examples use made-up numbers to teach the calculation. Not a clinical or legal guide: current Colombian rules are in the official sources.

Sources: [Maternal mortality ratio (per 100 000 live births)](https://www.who.int/data/gho/indicator-metadata-registry/imr-details/26) (World Health Organization, 2026); [Principles of Epidemiology | Lesson 3 - Section 3](https://archive.cdc.gov/www_cdc_gov/csels/dsepd/ss1978/lesson3/section3.html) (Centers for Disease Control and Prevention, 2012); [Lineamientos nacionales para la vigilancia en salud pública 2026 (vigilancia basada en eventos predefinidos)](https://www.ins.gov.co/BibliotecaDigital/lineamientos-nacionales-2026-fe-de-erratas.pdf) (Instituto Nacional de Salud (INS), Colombia, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/epidemiology/maternal-mortality-ratio/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/epidemiology/maternal-mortality-ratio/