Do Abortion rate (legal, reported) and DTP3 immunisation go together across countries?

Across 44 countries the link before adjusting for anything is r = -0.34, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.02.

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

Comparing each country only with itself across 2008-2024, and setting aside what happened worldwide in each year, the link is -0.104 (42 countries, 608 country-years). Using year-to-year changes, it is +0.073.

Does Abortion rate (legal, reported) cause DTP3 immunisation?

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.

Abortion rate (legal, reported) vs. DTP3 immunisation

Holds up after adjusting for income

Across 44 countries, Abortion rate (legal, reported) and DTP3 immunisation rise and fall together at r = -0.34 (on a scale from −1 to +1, where 0 means no link). It holds up almost unchanged when only countries with similar income (GDP per person) are compared (r = -0.35, q = 0.048, allowing for the many pairs tested). Caution: sign flips when a single country is removed.

Comparing countries across the middle half of abortion rate (legal, reported), 5.75 to 13.2 per 1,000 women aged 15-49, dtp3 immunisation is worse by 3.59% of children aged 12-23 months at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 3.55% of children aged 12-23 months.

Link before adjusting (r)-0.340p = 0.024 · 44 countries

After adjusting for national income-0.345p = 0.023 · likely range [-0.59, -0.05]

p, allowing for regions0.005standard error 0.046 · 4 regions

Check for luck (q)0.048across 14,952 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.

Abortion rate (legal, reported) · per 1,000 women aged 15-49link with income -0.03 · independent

DTP3 immunisation · % of children aged 12-23 monthslink with income +0.53 · 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	-0.340	0.024	44
By rank (Spearman), not adjusted	-0.018	0.907	44
Standard (Pearson), adjusted for national income	-0.345	0.023	44
By rank (Spearman), adjusted for national income	-0.024	0.880	44

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 44 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: -0.006 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.454 (without RUS) to +0.106 (without AZE). 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: AZE (+0.452).

Fragile: this link may not hold up.

sign flips when a single country is removed
leave-one-out range spans 0.56 in r
correlation moves sharply once outliers are trimmed
sign flips once outliers are trimmed

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
Europe & Central Asia	38	-0.38

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	15	-0.71
Middle third	14	+0.10
Richest third	15	+0.53

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	32	+0.21

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 = +0.039 after dropping 2 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.

Loading…

Over time, within countries

Everything above compares countries with each other at one moment. This section compares each country only with itself over 17years. 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 = -0.104, 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 abortion rate (legal, reported) moved did not tend to see their dtp3 immunisation move with it.

Across countries (adjusted)-0.345for comparison

Within countries+0.043each country vs itself

…and vs the same year elsewhere-0.104q = 0.723 · 42 countries

Year-on-year changes+0.073q = 0.499

608 country-years (one country in one year), 42 countries, 2008–2024, about 15 years each on average. Share of the variation that happens within countries over time: 17% for Abortion rate (legal, reported), 32% for DTP3 immunisation. 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): -0.104. 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 1,000 women aged 15-49	% of children aged 12-23 months	Years
Azerbaijan AZE	29.1	51%	2024
Russian Federation RUS	28.2	97%	2013, 2024
Sweden SWE	15.7	96%	2024
France FRA	15	96%	2019, 2024
Mongolia MNG	14.8	96%	2024
Seychelles SYC	14.7	94%	2024
Bulgaria BGR	14.2	94%	2021, 2024
Kazakhstan KAZ	13.8	98%	2021, 2024
New Zealand NZL	13.7	89%	2023, 2024
Georgia GEO	13.5	86%	2024
Norway NOR	13.3	97%	2011, 2024
United Kingdom GBR	13.2	92%	2016, 2024
Uruguay URY	12.9	94%	2022, 2024
Iceland ISL	12.8	94%	2018, 2024
Moldova MDA	12.7	86%	2023, 2024

United Nations Statistics Division, Demographic Yearbook, 2017 to 2024 editions: tables of marriages and crude marriage rates, of divorces and crude divorce rates, by urban/rural residence, and of legally induced abortions. Women aged 15 to 49 from the World Bank, World Development Indicators (CC BY 4.0).
World Bank, World Development Indicators

Sources

Abortion rate (legal, reported)

Legal abortions per 1,000 women aged 15-49

United Nations Statistics Division · UNdata terms of use · updated annual (each edition covers the latest five years)

Legal abortions reported to the UN Demographic Yearbook, per 1,000 women aged 15 to 49 (women of childbearing age, counted by the World Bank). Only countries where abortion is legal on broad grounds and the national count covers the whole country are included. That is mostly Europe, the former Soviet Union and a few others, such as Japan, Cuba and New Zealand. Countries whose counts cover only hospitals, only medical reasons or only complications are left out, and so is any year a footnote says is missing part of the country (several years for Italy). Abortions outside the official system, such as pills bought online, are not counted anywhere. So the figure is a floor, not a full count. Where abortion is banned, there is no figure at all, which is not the same as no abortions. No "better" direction is set.

DTP3 immunisation

Immunization, DPT (% of children ages 12-23 months)

WHO and UNICEF · CC BY 4.0 · updated quarterly

Three doses of the diphtheria, tetanus and whooping cough (pertussis) vaccine, the standard measure of a routine vaccination system. Measles coverage is published the same way and moves with it almost exactly, so only one of the two is here.

How this was computed

Data used: most recent value in 2010-2025; values come from 2011–2024. 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 4 World Bank regions. The q-value corrects for testing all 14,952 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Abortion rate (legal, reported) and DTP3 immunisation

This page shows that two measures go together. It does not show that Abortion rate (legal, reported) changes DTP3 immunisation, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.