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.
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.
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.
Connections
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) (World Health Organization, 2026); Principles of Epidemiology | Lesson 3 - Section 3 (Centers for Disease Control and Prevention, 2012); Lineamientos nacionales para la vigilancia en salud pública 2026 (vigilancia basada en eventos predefinidos) (Instituto Nacional de Salud (INS), Colombia, 2026).
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Representative model, for educational purposes only.