Do Maternal mortality and Median age go together across countries?

Across 187 countries the link before adjusting for anything is r = -0.68, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.85.

Does the link hold within countries over time, not just across countries?

Comparing each country only with itself across 1990-2023, and setting aside what happened worldwide in each year, the link is +0.267 (194 countries, 6,596 country-years). Using year-to-year changes, it is +0.024.

Does Maternal mortality cause Median age?

This analysis cannot answer that. It shows only that the two go together. A link between two country measures, adjusted or not, does not show that either one changes the other. Country figures also say nothing about individual people.

Maternal mortality vs. Median age

Fades after adjusting for income

Across 187 countries, Maternal mortality and Median age rise and fall together at r = -0.68 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.22, which could easily be chance (q = 0.18, allowing for the many pairs tested, and allowing for countries in the same region being alike). So the first figure mostly shows richer countries differing from poorer ones, not a link between these two things.

Comparing countries across the middle half of median age, 21 to 37.8 years, maternal mortality is better by 197 per 100,000 live births at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 84.7 per 100,000 live births.

Link before adjusting (r)-0.681p = 7.9e-27 · 187 countries

After adjusting for national income-0.217p = 0.003 · likely range [-0.35, -0.08]

p, allowing for regions0.015standard error 0.064 · 7 regions

Check for luck (q)0.176across 12,497 pairs

How to read these.r runs from −1 (one goes up as the other goes down) to +1 (they rise together), and 0 means no link. Adjusting for national income means comparing countries with the same GDP per person, so differences in wealth can’t explain the link. Income is used in percentage terms, since an extra $1,000 means more to a poor country than to a rich one. p is how likely a link this strong would be if there were really none. Below 0.05 means it is unlikely to be chance. Very small values are written in short form: 1.1e-32 means a decimal point followed by 31 zeros and then 11, so very close to zero. The likely range is where the true figure probably lies, and a range that crosses zero means the link could easily be chance. Countries in the same region tend to resemble each other, so the third figure allows for that, which gives a fairer p. The standard error is the typical size of the error in r. Finally, testing this many pairs means some will look strong by luck alone. A q below 0.05 means this link is unlikely to be one of those.

Maternal mortality · per 100,000 live birthslink with income -0.85 · proxy

Median age · yearslink with income +0.86 · proxy

Both of these rise and fall closely with national income, so a strong link between them before adjusting was close to certain. Read the adjusted figure, not the first one.

“Link with income” is how closely each measure tracks GDP per person across countries, from −1 to +1.

Every country as a dot

best-fit line line after adjusting

Four ways to measure the link

Method	r	p	Countries
Standard (Pearson), not adjusted	-0.681	7.9e-27	187
By rank (Spearman), not adjusted	-0.854	1.8e-54	187
Standard (Pearson), adjusted for national income	-0.217	0.003	187
By rank (Spearman), adjusted for national income	-0.448	1.5e-10	187

The rank version uses only each country’s place in line, from lowest to highest, so a few extreme countries count for less. The adjusted and unadjusted versions use the same 187 countries: those that report both measures and GDP per person. So the gap between them comes from the adjustment, not from a change in which countries are counted. Drop in the size of r after adjusting: +0.464 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.233 (without LBR) to -0.185 (without NGA). The bar above shows that range on a scale from −1 to +1, with the solid line at the full result. The single country that moves r most: NGA (+0.032).

Within each region

Countries are not separate, unrelated cases, and neighbors share a lot. A link that holds inside each region is far more believable than one that shows up only when comparing regions.

	n	r
East Asia & Pacific	29	-0.31
Europe & Central Asia	50	-0.25
Latin America & Caribbean	32	-0.21
Middle East, North Africa, Afghanistan & Pakistan	22	-0.14
Sub-Saharan Africa	46	-0.25

By income third

If the link shows up only in the richest third of countries, it is a feature of rich countries, not a general pattern.

	n	r
Poorest third	63	-0.40
Middle third	62	-0.52
Richest third	62	-0.47

By largest religious group

Countries grouped by a label they share, such as main religion, rather than by a number. Groups of fewer than twelve countries are not shown. These groups differ in income, region and history all at once. So a gap between them is a place to start asking questions, not an answer.

	n	r
Christians	109	-0.17
Muslims	49	-0.42

By last european coloniser

	n	r
France	25	-0.54
Never a European colony	21	+0.07
Spain	20	-0.68
United Kingdom	63	-0.29

Without outliers (countries far outside the middle half of countries on either measure, by more than one and a half times the width of that middle half): r = -0.329 after dropping 19 countries.

Two series, one country

Both measures over the years for one country you pick. The two charts are stacked so they share only the years along the bottom.

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Over time, within countries

Everything above compares countries with each other at one moment. This section compares each country only with itself over 34years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.

The link shows up within countries over time (r = +0.267) but mostly disappears in year-to-year changes (r = +0.024). That points to slow trends particular to each country, not the two measures moving together from year to year.

Across countries (adjusted)-0.217for comparison

Within countries-0.145each country vs itself

…and vs the same year elsewhere+0.267q = 2.0e-5 · 194 countries

Year-on-year changes+0.024q = 0.000

Read with care.

Almost all of this indicator's variation is between countries, not within them, so the within-country estimate rests on a small part of the data.
The association is much weaker in year-on-year changes than in levels, which points to shared country-specific trends.

6,596 country-years (one country in one year), 194 countries, 1990–2023, about 34 years each on average. Share of the variation that happens within countries over time: 9% for Maternal mortality, 31% for Median age. The margins of error allow for each country appearing many times, and for each year’s value being close to the year before.

Year-to-year changes are a cautious test, not a final answer. Looking only at changes from one year to the next removes each country’s own trends. But it also makes measurement mistakes louder, which pulls the results toward zero. A near-zero result here is weak evidence of no link, not proof.

With one measure years behind the other

Same year (lag 0): +0.267. A peak away from zero does not show which comes first. These series change slowly — this year’s value is close to last year’s. That makes the curve smooth and nearly symmetric, whatever produced the data. Even a sharp peak at one lag (a gap of some years) would not prove that one measure changes the other.

This curve peaks at the edge of the window (lag -10), so it is still drifting where the search stops. That pattern usually reflects a slow trend left over in the data, not a link with real timing. The peak value should not be read as the “true” link at the right lag.

The data

	per 100,000 live births	years	Years
Nigeria NGA	993	17.8	2023
Chad TCD	748	15.4	2023
Central African Republic CAF	692	14.3	2023
Liberia LBR	628	18.4	2023
Somalia, Fed. Rep. SOM	563	15.4	2023
Afghanistan AFG	521	16.9	2023
Benin BEN	518	17.8	2023
Guinea-Bissau GNB	505	18.9	2023
Guinea GIN	494	18	2023
Lesotho LSO	478	21.4	2023
Madagascar MDG	445	18.9	2023
Congo, Dem. Rep. COD	427	15.8	2023
Burundi BDI	392	15.9	2023
Mauritania MRT	381	17.1	2023
Mali MLI	367	15.5	2023

World Bank, World Development Indicators
United Nations, Department of Economic and Social Affairs, Population Division: World Population Prospects 2024 and Estimates and Projections of Women of Reproductive Age Who Are Married or in a Union

Sources

Maternal mortality

Maternal mortality ratio, modelled estimate (per 100,000 live births)

WHO and the UN Maternal Mortality Estimation Inter-Agency Group · CC BY 4.0 · updated quarterly

Estimated with a model, like stunting, and for the same reason. Deaths in childbirth are rare in small countries with weak death records, so the agencies estimate rather than count.

Median age

Median age of the population

United Nations Department of Economic and Social Affairs, Population Division · via Our World in Data · CC BY 3.0 IGO · updated biennial

The age that splits a population in half: half are older and half are younger. The shares aged under 15 and over 65 are already on the site. All three are treated as measuring the same thing. They are readings of the same age pyramid, so they are bound to match, and their agreement is not a finding. No "better" direction is set.

How this was computed

Data used: most recent value in 2010-2025; values come from 2023. To adjust for income, each measure is first predicted from GDP per person (in percentage terms, on a log scale) with a straight-line fit. Only what is left over is then compared. This is called a partial correlation. The line is drawn the standard way (ordinary least squares), which picks the line that comes closest to all the countries at once. The error margins allow for countries in the same region resembling each other, using 7 World Bank regions. The q-value corrects for testing all 12,497 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Maternal mortality and Median age

This page shows that two measures go together. It does not show that Maternal mortality changes Median age, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.