Do Anaemia in women and Contraceptive use (modern methods) go together across countries?

Across 141 countries the link before adjusting for anything is r = -0.63, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.64.

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

Comparing each country only with itself across 2000-2023, and setting aside what happened worldwide in each year, the link is -0.140 (59 countries, 443 country-years). Using year-to-year changes, it is —.

Does Anaemia in women cause Contraceptive use (modern methods)?

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.

Anaemia in women vs. Contraceptive use (modern methods)

Fades after adjusting for income

Across 141 countries, Anaemia in women and Contraceptive use (modern methods) rise and fall together at r = -0.63 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) leaves r = -0.49, which could easily be chance (q = 0.10, allowing for the many pairs tested, and allowing for countries in the same region being alike).

Comparing countries across the middle half of contraceptive use (modern methods), 23.9% to 56.9%, anaemia in women is better by 11.4% of women aged 15-49 at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 7.85% of women aged 15-49.

Link before adjusting (r)-0.635p = 2.9e-17 · 141 countries

After adjusting for national income-0.486p = 1.2e-9 · likely range [-0.60, -0.35]

p, allowing for regions0.003standard error 0.100 · 7 regions

Check for luck (q)0.104across 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.

Anaemia in women · % of women aged 15-49link with income -0.67 · high

Contraceptive use (modern methods) · %link with income +0.46 · 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	-0.635	2.9e-17	141
By rank (Spearman), not adjusted	-0.638	1.8e-17	141
Standard (Pearson), adjusted for national income	-0.486	1.2e-9	141
By rank (Spearman), adjusted for national income	-0.496	4.4e-10	141

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 141 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: +0.149 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.519 (without IND) to -0.471 (without MDV). 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: IND (-0.033).

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	22	+0.01
Europe & Central Asia	30	-0.26
Latin America & Caribbean	23	-0.55
Middle East, North Africa, Afghanistan & Pakistan	15	-0.39
Sub-Saharan Africa	44	-0.65

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	47	-0.57
Middle third	47	-0.31
Richest third	47	-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	83	-0.51
Muslims	43	-0.28

By last european coloniser

	n	r
France	23	-0.60
Never a European colony	21	-0.53
Spain	17	-0.51
United Kingdom	45	-0.28

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 = -0.486 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 24years. 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 = -0.140, 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 anaemia in women moved did not tend to see their contraceptive use (modern methods) move with it.

Across countries (adjusted)-0.486for comparison

Within countries-0.417each country vs itself

…and vs the same year elsewhere-0.140q = 0.115 · 59 countries

Year-on-year changes—q = —

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.
Much of the within-country association disappears once shared global year effects are removed, which points to a common worldwide trend rather than a country-level relationship.

443 country-years (one country in one year), 59 countries, 2000–2023, about 8 years each on average. Share of the variation that happens within countries over time: 9% for Anaemia in women, 4% for Contraceptive use (modern methods). 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): -0.140. 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 +6), 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

	% of women aged 15-49	%	Years
Gabon GAB	59.9%	17.3%	2023, 2021
Mali MLI	56.5%	16.4%	2023, 2018
Mauritania MRT	54.5%	12.8%	2023, 2021
India IND	53.7%	56.4%	2023, 2021
Cote d'Ivoire CIV	51.4%	25.2%	2023, 2022
Benin BEN	50%	16.9%	2023, 2022
Niger NER	47.1%	13.9%	2023
Mozambique MOZ	47%	25.4%	2023
Congo, Rep. COG	46.7%	18.3%	2023, 2015
Chad TCD	46.5%	6.7%	2023, 2019
Pakistan PAK	46.5%	25%	2023, 2018
Somalia, Fed. Rep. SOM	46.2%	0.9%	2023, 2019
Gambia, The GMB	46.1%	17.1%	2023, 2020
Haiti HTI	45.9%	31.8%	2023, 2017
Guinea-Bissau GNB	45.7%	20.2%	2023, 2019

World Bank, World Development Indicators
World Bank, World Development Indicators

Sources

Anaemia in women

Prevalence of anaemia among women of reproductive age (% of women ages 15-49)

World Health Organization · CC BY 4.0 · updated quarterly

Contraceptive use (modern methods)

Contraceptive prevalence, any modern method (% of married women ages 15-49)

World Bank · CC BY 4.0 · updated quarterly

The same survey share as contraceptive use by any method, counting only modern methods: the pill, condoms, IUDs, implants, injections and sterilisation. Most countries have a survey only every few years.

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 14,952 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Anaemia in women and Contraceptive use (modern methods)

This page shows that two measures go together. It does not show that Anaemia in women changes Contraceptive use (modern methods), or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.