Iron deficiency with and without anemia in pregnancy: A scoping review of prevalence and perinatal impact
Bibliographic record
Abstract
BACKGROUND: The prevalence of iron deficiency with anemia and iron deficiency without anemia (IDWA) during pregnancy have not been summarized, and evidence of the direct association of IDWA with adverse perinatal outcomes (APO) are unknown. OBJECTIVES: To summarize the prevalence of iron deficiency with and without anemia in pregnancy and determine if there is reported evidence of an effect for IDWA on adverse perinatal outcomes (APO). SEARCH STRATEGY: Literature search was completed using four electronic databases, with no restrictions on date or language. SELECTION CRITERIA: Selected were observational studies, randomized controlled trials (RCTs), systematic reviews, meta-analyses, narrative reviews on iron deficiency (ID) in pregnancy, published from inception to May 30, 2025. DATA COLLECTION AND ANALYSIS: Two independent reviewers screened article titles, abstracts, and full texts. The PRISMA guideline for scoping reviews was followed. A narrative summary was performed. RESULTS: A total of 33 studies were included comprising five RCTs, 27 observational studies, and one narrative summary, involving 84 618 pregnant women. The prevalence of ID varied from 1.2%-71.0%; 1.2%-55.6% (IDA), and 1.6%-71.0% (IDWA). Two studies exclusively reported on IDWA and APO. The first study reported on preterm birth (adjusted odds ratio [aOR] 0.9, 95% confidence interval [CI]: 0.6-1.4), stillbirth (aOR 4.0, 95% CI: 1.0-14.3), low birthweight (aOR 0.6, 95% CI: 0.4-1.0), and small for gestational age (aOR 0.8, 95% CI: 0.5-1.2) in IDWA versus iron replete. The second study reported an adjusted birthweight of 3140 g (95% CI: 3067-3213) in IDWA and 3202 g (95% CI: 3164-3240) in iron replete individuals (P = 0.16). CONCLUSIONS: Prevalence of ID varied widely, with substantial variability in biomarkers and diagnostic cut-offs used in case definition. There were limited studies reporting on IDWA and its association with APO. Further research is needed to establish an association and to inform early screening and determine whether treating IDWA improves perinatal outcomes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.021 | 0.092 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.008 | 0.008 |
| Bibliometrics | 0.023 | 0.019 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.005 | 0.004 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".