Meta-analysisindependent cross-checkabstract checked★ key study I-SUP-101 in-depth review
Iron tablets in pregnancy: updated Cochrane review
Daily oral iron supplementation during pregnancy.
Overview
Finkelstein JL et al.. Cochrane Database Syst Rev 2024 · PMID 39145520 · DOI 10.1002/14651858.CD004736.pub6
In 57 trials with almost 49,000 pregnant women, daily iron reduced iron-deficiency anaemia at term from 18.4% to 5.0% and slightly reduced low birthweight.
Does the study support the specific claim? No · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
To summarise all trials of daily iron tablets in pregnancy.
- How was the study done?
Systematic review and meta-analysis of randomised trials (Cochrane, 2024).
- How many people, animals or samples were studied?
57 trials, 48,971 women.
- What was actually found?
Less anaemia and iron deficiency at term; slightly fewer low-birthweight babies; no clear effect on deaths or preterm birth.
- How large was the observed effect?
Iron-deficiency anaemia RR 0.41 (0.26-0.63); anaemia RR 0.30 (0.20-0.47); low birthweight RR 0.84 (0.72-0.99).
- What do the results mean in everyday life?
Iron tablets in pregnancy work for their main purpose: preventing and correcting iron deficiency and anaemia.
- What are the study's limitations?
Mostly preventive use; harms poorly reported; heterogeneity.
- What does it say about Elawady's specific claim?
Contradicts the claim that iron supplements are forbidden or unnecessary in pregnancy.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
It does not show that every pregnant woman needs iron, nor that iron prevents deaths.
Scientific in-depth review
1. Full reference
- Authors
- Finkelstein JL et al.
- Journal
- Cochrane Database Syst Rev
- Year
- 2024
- Identifier
- PMID 39145520 DOI 10.1002/14651858.CD004736.pub6 · PMC11325660
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
none Crossref update-to: new version of an earlier Cochrane review (not a retraction).
- Extent checked
- abstract only
- Conflicts of interest and funding
COI statement in record: We certify that we have no affiliations with or involvement in any organisation or entity with a direct financial interest in the subject matter of the review (e.g. employment, consultancy, stock ownership, honoraria, expert testimony). Dr Julia L Finkelstein is a principal investigator on research ; funding listed: World Health Organization
2. Research question
Effects of daily oral iron (alone, with folic acid, or with other micronutrients) during pregnancy on maternal and infant outcomes.
3. Study design and population
- Study design
- Meta-analysis – Cochrane systematic review and meta-analysis of randomised and quasi-randomised trials (update of CD004736)
- Population
Pregnant women of any age and parity
- Country
Multinational (trials in high-, middle- and low-income countries; 19 in malaria-risk settings)
- Period
Search to 18 January 2024
- Sample size
57 trials, 48,971 women
- Inclusion and exclusion criteria
Randomised or quasi-randomised trials of daily oral iron, iron + folic acid or iron + other micronutrients vs placebo/no iron; trustworthiness screening applied
4. Methods and endpoints
- Exposure / intervention
Daily oral iron (with or without folic acid)
- Comparator
Placebo or no iron (same co-interventions)
- Endpoints
Maternal anaemia, iron deficiency, iron-deficiency anaemia at term, maternal death, adverse effects, low birthweight, preterm birth, neonatal death, congenital anomalies
- Statistical methods
Random-effects meta-analysis (average treatment effect); GRADE for primary outcomes
5. Actual results
- Results
Iron vs no iron: maternal anaemia at term 4.0% vs 7.4%, RR 0.30 (95% CI 0.20-0.47; 14 trials, 13,543 women; low certainty); iron deficiency at term 44.0% vs 66.0%, RR 0.51 (0.38-0.68; low); iron-deficiency anaemia at term 5.0% vs 18.4%, RR 0.41 (0.26-0.63; moderate); maternal death RR 0.57 (0.12-2.69; moderate, little or no difference); adverse effects 21.6% vs 18.0%, RR 1.29 (0.83-2.02; very low); low birthweight 5.2% vs 6.1%, RR 0.84 (0.72-0.99; moderate); preterm birth RR 0.93 (0.84-1.02; moderate); neonatal death RR 0.98 (0.77-1.24; low). Iron + folic acid vs folic acid: maternal anaemia at term 12.1% vs 25.5%, RR 0.44 (0.30-0.64; moderate); birthweight +57.73 g (7.66-107.79; moderate).
- Absolute risks
Reported as event proportions (see results); recalculated ARR for iron-deficiency anaemia at term 13.4 percentage points (NNT about 7) and for low birthweight 0.9 points (NNT about 111) - illustrative (stats/C-SUP-09_finkelstein2024.py).
- Authors' conclusion
Daily oral iron supplementation during pregnancy may reduce maternal anaemia and iron deficiency at term; for other maternal and infant outcomes there was little or no difference or the evidence was uncertain.
6. Strengths
- Most recent Cochrane update (2024) with trustworthiness screening
- Large number of trials and participants
- GRADE certainty ratings per outcome
7. Weaknesses
- Mainly preventive supplementation in mixed populations, not treatment of diagnosed anaemia
- High heterogeneity; low certainty for some outcomes
- Harms poorly reported (very low certainty)
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Cochrane methods; pre-specified protocol; risk of bias in included trials varies; judgement simplified.
9. Assessment of the statistical interpretation
Relative effects on anaemia and iron deficiency are large and consistent; the low-birthweight benefit is small in absolute terms (about 1 percentage point). The crude ratio of pooled percentages for anaemia (0.54) differs from the random-effects RR (0.30), so absolute numbers should be read as illustrative.
10. Relevance to the specific claim
Directly contradicts the claim that iron supplements are useless or forbidden in pregnancy; supersedes I-SUP-04 (2015 version).
11. Independent contrary findings
Benefit on hard clinical outcomes (maternal death, preterm birth, neonatal death) is not shown; harms (gastrointestinal effects, high haemoglobin) are uncertain.
12. Transferability to Germany and Europe
Applicable; European antenatal care tests haemoglobin and treats iron deficiency.
13. Overall methodological judgement
High-quality evidence that iron supplementation prevents and corrects iron deficiency and anaemia in pregnancy; certainty for clinical outcomes is lower.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Effects of routine iron in iron-replete women in high-income settings; long-term child outcomes.
15. Linked fact checks
- There is no such thing as iron supplements: they are forbidden even for a pregnant woman with anaemia, because a diet that needs supplements is deficient. – Studies contradicting or limiting the claim
- No one needs vitamins or supplements: 'there is no such thing as dietary supplements', the body makes its own vitamins, and vitamins are on the forbidden list. – Studies contradicting or limiting the claim