Meta-analysisindependent cross-checkabstract only checked★ key study I-SUP-04 in-depth review
Iron in pregnancy (Cochrane)
Daily oral iron supplementation during pregnancy.
Overview
Peña-Rosas JP et al.. Cochrane Database Syst Rev 2015 · PMID 26198451 · DOI 10.1002/14651858.CD004736.pub5
Daily iron reduced anaemia at term by 70%.
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?
Iron in pregnancy.
- How was the study done?
Cochrane.
- How many people, animals or samples were studied?
43,274 women.
- What was actually found?
Less anaemia.
- How large was the observed effect?
RR 0.30.
- What do the results mean in everyday life?
Iron helps pregnant women.
- What are the study's limitations?
Low-quality evidence.
- What does it say about Elawady's specific claim?
Contradicts C-SUP-09.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Birth outcome benefits.
Scientific in-depth review
1. Full reference
- Authors
- Peña-Rosas JP et al.
- Journal
- Cochrane Database Syst Rev
- Year
- 2015
- Identifier
- PMID 26198451 DOI 10.1002/14651858.CD004736.pub5
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
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). Juan Pablo Peña‐Rosas was author of an excluded study on iron and folic acid intermittent supplementation. Luz Maria De‐Regil is full‐time staff member of the Micronutrient Initiative, an International Organization that delivers vitamin interventions to children, women of reproductive age and pregnant women, including iron and folic acid supplementation in eight countries in Africa and South East Asia. Disclaimer: Juan Pablo Peña‐Rosas is currently a staff member of the World Health Organization. Maria Nieves Garcia‐Casal is a Consultant working for the World Health Organization. The authors alone are responsible for the views expressed in this publication and they do not necessarily represent the decisions, policy or views of the World Health Organization. Therese Dowswell's institution (the University of Liverpool) has received an NIHR Cochrane Programme Grant and Therese is currently employed on this project. As part of her role, Therese helps volunteer review teams prepare Cochrane reviews. This review is not part of that portfolio of reviews. In the last 36 months Therese has received funding from the WHO to work on other Cochrane reviews. The Funders have no influence on the content or conclusions of the reviews Therese works on.
2. Research question
Effects of daily oral iron supplements in pregnancy
3. Study design and population
- Study design
- Meta-analysis – Cochrane systematic review of RCTs
- Population
Pregnant women
- Country
Multinational (incl. malaria areas)
- Period
to Jan/Feb 2015
- Sample size
61 trials; 44 trials, 43,274 women
- Inclusion and exclusion criteria
RCTs/quasi-RCTs
4. Methods and endpoints
- Exposure / intervention
Daily iron ± folic acid ± micronutrients
- Comparator
No iron/placebo
- Endpoints
Maternal anaemia, iron deficiency, birth outcomes
- Statistical methods
Random effects; GRADE
5. Actual results
- Results
Maternal anaemia at term RR 0.30 (0.19–0.46, low quality); iron-deficiency anaemia RR 0.33 (0.16–0.69); iron deficiency RR 0.43 (0.27–0.66); low birthweight 8.4% vs 10.3%, RR 0.84 (0.69–1.03, n.s.); preterm RR 0.93 (n.s.); higher risk of Hb >130 g/L.
- Absolute risks
Low birthweight 8.4% vs 10.3% (n.s.)
- Authors' conclusion
Supplementation reduces maternal anaemia and iron deficiency; effects on other outcomes less clear.
6. Strengths
- Cochrane
- Large
7. Weaknesses
- Heterogeneity
- Low-quality evidence for main outcomes
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
9. Assessment of the statistical interpretation
10. Relevance to the specific claim
11. Independent contrary findings
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Iron reduces anaemia in pregnancy.
| 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 | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
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