Do Birth rate and Liberal democracy go together across countries?

Across 168 countries the link before adjusting for anything is r = -0.52, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.51.

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

Comparing each country only with itself across 1990-2024, and setting aside what happened worldwide in each year, the link is -0.082 (174 countries, 6,049 country-years). Using year-to-year changes, it is -0.009.

Does Birth rate cause Liberal democracy?

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.

Birth rate vs. Liberal democracy

Fades after adjusting for income

Across 168 countries, Birth rate and Liberal democracy rise and fall together at r = -0.52 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.16, which could easily be chance (q = 0.49, 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. Caution: direction is not consistent across regions.

Comparing countries across the middle half of liberal democracy, 0.127 to 0.615 points, birth rate is 9.82 per 1,000 people lower at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 1.82 per 1,000 people.

Link before adjusting (r)-0.523p = 3.7e-13 · 168 countries

After adjusting for national income-0.163p = 0.035 · likely range [-0.31, -0.01]

p, allowing for regions0.194standard error 0.111 · 7 regions

Check for luck (q)0.494across 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.

Birth rate · per 1,000 peoplelink with income -0.85 · proxy

Liberal democracy · index (0-1)link with income +0.52 · moderate

“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	-0.523	3.7e-13	168
By rank (Spearman), not adjusted	-0.512	1.3e-12	168
Standard (Pearson), adjusted for national income	-0.163	0.035	168
By rank (Spearman), adjusted for national income	-0.162	0.036	168

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 168 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: +0.359 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.183 (without CHN) to -0.142 (without SAU). 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: SAU (+0.021).

Fragile: this link may not hold up.

direction is not consistent across regions

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	21	+0.34
Europe & Central Asia	49	-0.16
Latin America & Caribbean	23	-0.62
Middle East, North Africa, Afghanistan & Pakistan	21	-0.09
Sub-Saharan Africa	46	-0.57

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	56	-0.17
Middle third	56	-0.18
Richest third	56	-0.37

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	99	-0.18
Muslims	48	-0.30

By last european coloniser

	n	r
France	25	+0.04
Never a European colony	21	-0.47
Spain	19	-0.45
United Kingdom	49	-0.27

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 = -0.163 after dropping 0 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 35years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.

Within countries over time, there is no link that is clearly more than chance (r = -0.082, comparing each country only with itself over the years, and each year only with the same year elsewhere). Whatever the cross-country picture shows, countries whose birth rate moved did not tend to see their liberal democracy move with it.

Across countries (adjusted)-0.163for comparison

Within countries-0.205each country vs itself

…and vs the same year elsewhere-0.082q = 0.282 · 174 countries

Year-on-year changes-0.009q = 0.809

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.

6,049 country-years (one country in one year), 174 countries, 1990–2024, about 35 years each on average. Share of the variation that happens within countries over time: 8% for Birth rate, 10% for Liberal democracy. 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): -0.082. 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.

The data

	per 1,000 people	index (0-1)	Years
Central African Republic CAF	46.2	0.102	2024, 2025
Chad TCD	43.3	0.062	2024, 2025
Somalia, Fed. Rep. SOM	42.3	0.128	2024, 2025
Niger NER	41.4	0.177	2024, 2025
Congo, Dem. Rep. COD	40.9	0.115	2024, 2025
Mali MLI	39.5	0.15	2024, 2025
Angola AGO	37.2	0.163	2024, 2025
Mozambique MOZ	37	0.175	2024, 2025
Afghanistan AFG	35	0.018	2024, 2025
Tanzania TZA	34.8	0.297	2024, 2025
Uganda UGA	34.4	0.165	2024, 2025
Mauritania MRT	34	0.127	2024, 2025
Benin BEN	33.4	0.323	2024, 2025
Cameroon CMR	33.3	0.114	2024, 2025
Guinea GIN	33.3	0.095	2024, 2025

World Bank, World Development Indicators
Coppedge, M. et al., V-Dem Dataset, Varieties of Democracy (V-Dem) Project

Sources

Birth rate

Birth rate, crude (per 1,000 people)

World Bank · CC BY 4.0 · updated quarterly

Liberal democracy

Liberal democracy index

V-Dem Institute, University of Gothenburg · via Our World in Data · CC BY 4.0 · updated annual

Electoral democracy plus limits on the head of government, independent courts and protected personal freedoms. It contains the electoral democracy index as a part, so the two are built from the same numbers and bound to match.

How this was computed

Data used: most recent value in 2010-2025; values come from 2024–2025. 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 Birth rate and Liberal democracy

This page shows that two measures go together. It does not show that Birth rate changes Liberal democracy, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.