Iron for Pregnancy
For pregnancy, iron is one of the best-supported supplements: routine daily oral iron reliably prevents maternal anemia, and intravenous iron is an effective second-line treatment for established iron-deficiency anemia in the second and third trimesters. It is genuinely beneficial, but it is not a free-for-all supplement — the benefit is largest when iron is actually needed, and excess iron carries real risks.
Why this grade7-layer evidence engine
This earns a Moderate (A) grade because the evidence is unusually consistent across study quality, clinical bodies, and regulators, all pointing the same direction. For routine prevention, a large Cochrane systematic review of 44 trials (n=43,274; PMID 26198451) found daily oral iron cut maternal anemia at term by roughly 70% (RR 0.30) and nudged up birth weight (+31 g), though it showed no clear effect on preterm birth and only a borderline reduction in low birth weight. So the prevention case is strong for anemia and iron status, more modest for hard birth outcomes.
For pregnant women who already have iron-deficiency anemia, three 2024-era randomized trials and a meta-analysis support intravenous iron as a faster-acting second-line option from the second trimester on. RAPIDIRON (n=4,320; PMID 39909327) showed IV iron lowered low-birth-weight risk (RR 0.81) and more often restored a non-anemic state; IVON (n=1,056; PMID 39304237) and a small US pilot (PMID 34839481) showed quicker correction of anemia, and a meta-analysis of 10 trials (n=5,954; PMID 38167523) found greater hemoglobin gains, fewer transfusions (RR 0.60), and fewer gut side effects than oral iron.
Regulators and clinics reinforce this. The WHO recommends daily oral iron plus folic acid in antenatal care; the FDA, EFSA (normal oxygen transport), NIH, Mayo, Cleveland, and Harvard all back iron in pregnancy, with the Cleveland Clinic noting untreated anemia raises preterm and low-birth-weight risk. The nuance: the UK NHS is more cautious, saying diet usually suffices and supplements are warranted when blood tests confirm low iron, and US bodies (ACOG, USPSTF) favor screening-and-treating over blanket supplementation in well-nourished populations. Iron should not be self-prescribed at high doses without confirming deficiency (it is harmful in conditions like hemochromatosis or thalassemia), IV iron is not advised in the first trimester, and iron tablets must be kept away from children because overdose can be fatal.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.76
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status