Across 166 countries, Adolescent fertility and Birth registration rise and fall together at r = -0.70 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.39 (q = 0.026, allowing for the many pairs tested). Much of the first figure is that both measures rise with national income, but a weak negative link remains.
Comparing countries across the middle half of adolescent fertility, 8.27 to 66.4 births per 1,000 women aged 15-19, birth registration is worse by 23.2% of children under 5 at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 14.6% of children under 5.
Link before adjusting (r)-0.701p = 7.2e-26 · 166 countries
After adjusting for national income-0.385p = 3.2e-7 · likely range [-0.51, -0.25]
p, allowing for regions0.001standard error 0.070 · 7 regions
Check for luck (q)0.026across 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.
Adolescent fertility · births per 1,000 women aged 15-19link with income -0.81 · proxy
Birth registration · % of children under 5link with income +0.87 · 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
-0.701
7.2e-26
166
By rank (Spearman), not adjusted
-0.867
2.0e-51
166
Standard (Pearson), adjusted for national income
-0.385
3.2e-7
166
By rank (Spearman), adjusted for national income
-0.534
1.4e-13
166
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 166 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: +0.316 (a minus sign means it grew).
How solid is it?
Leaving out one country at a time, r ranges from -0.418 (without ETH) to -0.342 (without AGO). 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: AGO (+0.043).
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
24
-0.19
Europe & Central Asia
47
-0.09
Latin America & Caribbean
26
-0.36
Middle East, North Africa, Afghanistan & Pakistan
18
-0.26
Sub-Saharan Africa
44
-0.33
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
-0.27
Middle third
55
-0.69
Richest third
55
-0.67
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
103
-0.36
Muslims
41
-0.41
By last european coloniser
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
France
23
-0.47
Never a European colony
17
-0.07
Spain
19
-0.79
United Kingdom
51
-0.49
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 = -0.434 after dropping 16 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 0years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.
Not enough history inside each country to look at this over time. That needs countries measured for several years in a row, and at least one of these measures is measured too rarely.
The data
births per 1,000 women aged 15-19
% of children under 5
Years
Central African Republic CAF
161
44.8%
2024, 2019
Equatorial Guinea GNQ
153
53.5%
2024, 2011
Mozambique MOZ
152
55%
2024, 2015
Niger NER
142
63.9%
2024, 2012
Angola AGO
139
25%
2024, 2016
Mali MLI
136
86.7%
2024, 2018
Chad TCD
132
25.7%
2024, 2019
Madagascar MDG
129
73.8%
2024, 2021
Liberia LBR
125
66.3%
2024, 2020
Guinea GIN
117
62%
2024, 2018
Zambia ZMB
115
14%
2024, 2018
Somalia, Fed. Rep. SOM
115
5.9%
2024, 2020
Malawi MWI
113
67.2%
2024, 2016
Tanzania TZA
113
26.4%
2024, 2016
Congo, Rep. COG
108
95.9%
2024, 2015
World Bank, World Development Indicators World Bank, World Development Indicators
A measure of how far the state reaches: whether it knows a child exists. Based on surveys and sparse. It is near 100 across the rich world, so all the variation is at the other end.
How this was computed
Data used: most recent value in 2010-2025; values come from 2010–2024. 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 Adolescent fertility and Birth registration
This page shows that two measures go together. It does not show that Adolescent fertility changes Birth registration, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.
More links with Adolescent fertility or Birth registration