Iron
Vitamin & mineralAlso called · 8 names▾▴
ferrous sulfate, ferrous fumarate, iron salts, iron pills, iron supplement, iron supplements, oral iron, iron tablets
Iron mineral supplement
Herbs and supplements are not FDA-approved before sale. About these sources
- Capsule/tablet
Research strength: 4 / 5
MotherToBaby says iron at recommended daily amounts below the upper limit is not expected to raise birth-defect chances. Cochrane's 2024 review found likely reductions in maternal anemia and low birth weight, little or no change in preterm birth, and low-certainty evidence of little or no change in birth defects. ODS lists 27 mg/day for pregnancy and an adult upper limit of 45 mg/day; supplements at or above 45 mg/day may cause nausea and constipation. ACOG recommends low-dose iron starting in the first trimester and extra iron for diagnosed anemia; USPSTF says evidence is insufficient to assess routine supplements in asymptomatic pregnant people. FDA's boxed warning for Injectafer injection covers symptomatic low blood phosphate and phosphate checks for at-risk patients and repeat courses within three months; it does not apply to oral supplements. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby Iron fact sheetTeratology service
- NIH ODS Iron fact sheetUS government
- NIH ODS Pregnancy fact sheetUS government
- Cochrane 2024 review of daily oral iron in pregnancyResearch review
- ACOG Healthy Eating During PregnancyProfessional society
- USPSTF Iron Deficiency During Pregnancy recommendation
- FDA Injectafer boxed warningUS government
Research strength: 4 / 5
MotherToBaby says iron at recommended daily amounts below the upper limit is not expected to raise birth-defect chances. Cochrane's 2024 review found likely reductions in maternal anemia and low birth weight, little or no change in preterm birth, and low-certainty evidence of little or no change in birth defects. ODS lists 27 mg/day for pregnancy and an adult upper limit of 45 mg/day; supplements at or above 45 mg/day may cause nausea and constipation. ACOG recommends low-dose iron starting in the first trimester and extra iron for diagnosed anemia; USPSTF says evidence is insufficient to assess routine supplements in asymptomatic pregnant people. FDA's boxed warning for Injectafer injection covers symptomatic low blood phosphate and phosphate checks for at-risk patients and repeat courses within three months; it does not apply to oral supplements. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby Iron fact sheetTeratology service
- NIH ODS Iron fact sheetUS government
- NIH ODS Pregnancy fact sheetUS government
- Cochrane 2024 review of daily oral iron in pregnancyResearch review
- ACOG Healthy Eating During PregnancyProfessional society
- USPSTF Iron Deficiency During Pregnancy recommendation
- FDA Injectafer boxed warningUS government
Research strength: 4 / 5
MotherToBaby says iron at recommended daily amounts below the upper limit is not expected to raise birth-defect chances. Cochrane's 2024 review found likely reductions in maternal anemia and low birth weight, little or no change in preterm birth, and low-certainty evidence of little or no change in birth defects. ODS lists 27 mg/day for pregnancy and an adult upper limit of 45 mg/day; supplements at or above 45 mg/day may cause nausea and constipation. ACOG recommends low-dose iron starting in the first trimester and extra iron for diagnosed anemia; USPSTF says evidence is insufficient to assess routine supplements in asymptomatic pregnant people. FDA's boxed warning for Injectafer injection covers symptomatic low blood phosphate and phosphate checks for at-risk patients and repeat courses within three months; it does not apply to oral supplements. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby Iron fact sheetTeratology service
- NIH ODS Iron fact sheetUS government
- NIH ODS Pregnancy fact sheetUS government
- Cochrane 2024 review of daily oral iron in pregnancyResearch review
- ACOG Healthy Eating During PregnancyProfessional society
- USPSTF Iron Deficiency During Pregnancy recommendation
- FDA Injectafer boxed warningUS government
Iron — Breastfeeding
Research strength: 4 / 5
MotherToBaby says breastfeeding women can follow the recommended daily iron intake unless their provider advises otherwise. ODS lists 9 mg/day as the adult breastfeeding amount and 45 mg/day as the adult upper limit; supplements at or above 45 mg/day may cause nausea and constipation. LactMed says routine prenatal iron does not change milk iron; higher oral amounts for maternal anemia have little effect and are not expected to harm the infant. In Baykan et al.'s trial, infant iron measures were similar after mothers received 80 mg/day elemental iron or placebo; LactMed says maternal iron does not replace infant iron care. FDA's boxed warning for Injectafer injection covers symptomatic low blood phosphate and phosphate checks for at-risk patients and repeat courses within three months; it does not apply to oral supplements. Ask your provider about your situation.
Last reviewed: 2026-10-16
Sources
- MotherToBaby Iron fact sheetTeratology service
- LactMed Iron SaltsUS government
- NIH ODS Iron fact sheetUS government
- Baykan et al. 2006 maternal iron trial during lactationUS government
- AAP infant iron guidance summarized by American Family Physician
- Eneroth et al. 2010 infant micronutrient status trialUS government
- FDA Injectafer boxed warningUS government
Pregnancy
Finkelstein et al.'s 2024 Cochrane review included 57 trials and 48,971 pregnant women. In daily iron versus placebo or no iron comparisons, maternal anemia at term was 4.0% versus 7.4% (RR 0.30; 14 trials, 13,543 women; low-certainty evidence), and iron-deficiency anemia at term was 5.0% versus 18.4% (RR 0.41; 7 trials, 2,704 women; moderate-certainty evidence). Low birthweight was 5.2% versus 6.1% (RR 0.84; 12 trials, 18,290 infants; moderate-certainty evidence), and preterm birth was 7.6% versus 8.2% (RR 0.93; 11 trials, 18,827 infants; moderate-certainty evidence). For congenital anomalies, the review reported 41 versus 48 events (RR 0.88, 95% CI 0.58 to 1.33; 4 trials, 14,377 infants; low-certainty evidence), interpreted as little or no difference. The review concluded daily oral iron may reduce maternal anemia and iron deficiency at term, while other maternal and infant outcomes showed little difference or uncertain evidence. Overdose reports concern poisoning rather than routine prenatal amounts. McElhatton et al. (1991) reported 49 pregnancies with known overdose outcomes, including 2 spontaneous abortions. Tran et al. (2000) reviewed 61 intentional-overdose cases; stage-3 organ failure was associated with spontaneous abortion in 1 of 3 cases versus 1 of 56 in stages 0 to 2, while peak iron levels of at least 400 mcg/dL were not associated with increased spontaneous-abortion risk overall. Haynes et al. (2026) studied 135 nonanemic pregnant participants randomized to daily, alternate-day, or three-times-weekly 200 mg ferrous sulfate; the substudy measured iron biomarkers, not birth outcomes.
Breastfeeding
LactMed's April 2026 update says routine prenatal or multivitamin iron does not change milk iron and that higher oral doses used to treat maternal anemia have minimal effect on milk iron. Baykan et al. (2006) randomized healthy, nonanemic mothers of healthy term infants aged 10 to 20 days to 80 mg elemental iron daily or placebo for four months; 69 iron-group pairs and 63 placebo-group pairs completed the study. Maternal and infant blood measures, including infant serum iron and ferritin, were similar at follow-up. This trial tested a higher oral dose in nonanemic mothers, not treatment of maternal anemia. Eneroth et al. (2010) studied 1,066 six-month-old infants whose mothers received one of three regimens, all containing iron: 30 mg iron plus folic acid, 60 mg iron plus folic acid, or a multiple-micronutrient supplement with 30 mg iron. It found no other differential effects across those groups; it did not compare iron with no iron. An AAP infant recommendation summarized by American Family Physician (2011) calls for direct infant iron for full-term infants who are exclusively or mostly breastfed, starting at four months and continuing until iron-containing foods are introduced. This is separate from maternal iron intake.
ODS describes oral iron supplements as commonly using ferrous or ferric salts. The amount of elemental iron differs by salt: ODS lists ferrous fumarate as 33% elemental iron by weight, ferrous sulfate as 20%, and ferrous gluconate as 12%. ODS says the elemental iron amount is listed on supplement labels.
What was tested
Pregnancy trials studied daily oral iron alone or with folic acid or other micronutrients, compared with placebo or no iron, or compared with the same background supplements without iron. The Cochrane review notes that trials differed in participants' iron status, timing, dose, and co-supplements. The 2026 PANDA substudy compared daily, alternate-day, and three-times-weekly oral dosing in nonanemic pregnant participants and measured iron biomarkers rather than maternal or infant clinical outcomes.
Routine iron screening and supplementation for asymptomatic pregnant people
- Source A says
- ACOG recommends low-dose iron supplementation starting in the first trimester and screening for anemia in the first trimester and again at 24 to 28 weeks. ACOG's patient guidance lists 27 mg per day as the pregnancy amount and says most prenatal vitamins provide it. (NIH ODS Pregnancy fact sheet, ACOG Healthy Eating During Pregnancy)
- Source B says
- USPSTF gives an I statement for routine iron supplementation and screening in asymptomatic pregnant people because evidence is insufficient to assess the balance of benefits and harms. (USPSTF Iron Deficiency During Pregnancy recommendation)
- Why they differ
- ACOG's clinical guidance addresses prenatal care, anemia screening, and treatment. USPSTF evaluates whether population-level evidence can determine the benefits and harms of routine screening and supplements in asymptomatic people. The USPSTF statement does not apply to people with symptoms, severe malnutrition, or conditions that increase iron needs.
- What the evidence shows overall
- The Cochrane review found maternal blood-count benefits and a probable reduction in low birthweight, while several infant outcomes remained uncertain. ACOG's routine prenatal guidance and USPSTF's I statement can both be reported without treating insufficient evidence as advice to avoid iron or as a reason to withhold treatment for diagnosed anemia.
- ACOG lists 27 mg of iron per day during pregnancy, says most prenatal vitamins provide this amount, and says extra iron may be recommended when anemia is present. (ACOG)
- USPSTF says the evidence is insufficient to assess the balance of benefits and harms of routine iron supplements for asymptomatic pregnant people; its statement does not apply to people with symptoms or diagnosed anemia. (USPSTF)
General research, not specific to pregnancy.
ODS says iron needs vary by age and life stage, and very high amounts can cause serious poisoning.
- ODS sets the adult upper limit at 45 mg per day and says extremely high doses can cause severe intestinal injury, multiple organ failure, and death. (NIH ODS Iron fact sheet)
- The MHRA's June 2026 UK medicines-label guidance requires child-resistant packaging for licensed iron medicines with more than 24 mg elemental iron per dose and a warning that overdose may be fatal. (MHRA Label Warnings Guidance, June 2026)
- FDA added a boxed warning for symptomatic hypophosphatemia (low blood phosphate) with ferric carboxymaltose injection, including phosphate checks for at-risk patients and repeat courses within three months. EMA's September 2026 referral also concerns injectable iron and explicitly excludes iron taken by mouth. (FDA Injectafer boxed warning, EMA referral on injectable iron-containing medicines)
- MotherToBaby Iron fact sheetTeratology serviceSecondary
- NIH ODS Iron fact sheetUS governmentSecondaryPage dated 2025-09-04Independent check
- NIH ODS Pregnancy fact sheetUS governmentSecondaryPage dated 2025-04-03Independent check
- ACOG Healthy Eating During PregnancyProfessional societySecondaryIndependent check
- USPSTF Iron Deficiency During Pregnancy recommendationSecondaryPage dated 2024-08-20Independent check
- Finkelstein et al. 2024 Cochrane review of daily oral iron in pregnancyResearch reviewPrimaryPage dated 2024-08-15Independent check
- LactMed Iron SaltsUS governmentSecondaryPage dated 2026-04-15Independent check
- Baykan et al. 2006 maternal iron trial during lactationUS governmentPrimaryIndependent check
- Eneroth et al. 2010 maternal micronutrient trialUS governmentPrimaryPage dated 2010-01-06
- AAP infant iron guidance summarized by American Family PhysicianSecondaryPage dated 2011-03-01Independent check
- McElhatton et al. 1991 iron overdose pregnancy casesUS governmentPrimaryIndependent check
- Tran et al. 2000 intentional iron overdose pregnancy reviewUS governmentPrimaryIndependent check
- Haynes et al. 2026 PANDA iron dosing biomarker substudyUS governmentPrimaryPage dated 2026-07-14
- MHRA Label Warnings Guidance, June 2026UK governmentSecondary
- FDA Injectafer boxed warningUS governmentSecondaryPage dated 2026-09-01Independent check
- EMA referral on injectable iron-containing medicinesEU agencySecondaryPage dated 2026-09-04Independent checkEuropean guidance
Last reviewed 2026-10-16
Independent check 2026-10-16
Not yet clinician-reviewed
Ask your provider about your situation.