What is the recommended dosage of ferrous sulfate (iron supplement) for pregnant individuals with iron deficiency anemia?

Ferrous Sulfate Dosage in Pregnancy

For prevention, start 30 mg of elemental iron daily at the first prenatal visit; for treatment of confirmed iron deficiency anemia, prescribe 60-120 mg of elemental iron daily. 1, 2

Prevention (Primary Prophylaxis)

• All pregnant women should begin low-dose oral iron supplementation (30 mg elemental iron daily) at the first prenatal visit, regardless of anemia status. 1, 2
• Standard prenatal vitamins typically contain 30-48 mg of elemental iron, which satisfies this prophylactic requirement. 1, 2
• This preventive dose should continue throughout pregnancy unless anemia develops requiring higher therapeutic doses. 1, 2

Treatment of Confirmed Iron Deficiency Anemia

• Prescribe 60-120 mg of elemental iron daily for pregnant women with documented iron deficiency anemia. 1, 2
• Begin treatment immediately after confirming anemia with a repeat hemoglobin or hematocrit test if the patient is not acutely ill—do not delay for additional testing. 1, 2
• The most commonly used formulations are ferrous sulfate (300 mg tablets contain approximately 60 mg elemental iron), ferrous fumarate, or iron polymaltose complex. 2, 3

Monitoring and Dose Adjustment

• Recheck hemoglobin or hematocrit after 4 weeks of treatment. 1, 2
• Expected response: hemoglobin should increase by ≥1 g/dL or hematocrit by ≥3%. 1, 2
• Once hemoglobin normalizes for gestational age, reduce the dose back to 30 mg elemental iron daily for maintenance. 1, 2

Optimizing Absorption and Compliance

• Take iron supplements at bedtime to minimize gastrointestinal side effects. 2
• Separate iron from calcium supplements and antacids by several hours, as these significantly reduce iron absorption. 2
• Encourage consumption of vitamin C-rich foods with iron to enhance absorption. 1, 2
• Common side effects include nausea, constipation, darkening of stool, and possible tooth staining—these are expected and not harmful. 1, 2

When to Escalate Care

• If hemoglobin is <9.0 g/dL or hematocrit is <27.0%, refer to a physician experienced in managing anemia during pregnancy for further evaluation. 1, 2
• If anemia does not respond after 4 weeks of compliant treatment (no increase in hemoglobin by 1 g/dL), obtain additional testing including MCV, RDW, and serum ferritin. 1, 2
• In women of African, Mediterranean, or Southeast Asian ancestry, consider thalassemia minor or sickle cell trait as alternative diagnoses if anemia is unresponsive to iron. 1, 2

Special Populations Requiring Higher Vigilance

• Vegetarian women may require almost double the iron intake due to poor absorption of non-heme iron from plant sources. 1
• Non-Hispanic Black and Mexican American women have higher prevalence rates of iron deficiency and warrant closer monitoring. 1, 2
• Women with short interpregnancy intervals, gastrointestinal conditions affecting absorption (or taking antacids), or previous iron deficiency anemia need more aggressive supplementation. 1, 2

Postpartum Management

• Discontinue iron supplementation at delivery if no risk factors for postpartum anemia exist. 1, 2
• Screen for anemia at 4-6 weeks postpartum only if risk factors are present: anemia continuing through third trimester, excessive blood loss at delivery, or multiple birth. 1, 2
• If postpartum iron deficiency anemia is diagnosed, treat with 60-120 mg elemental iron daily and continue for 2-3 months after hemoglobin normalizes to replenish iron stores. 1, 2

Critical Pitfalls to Avoid

• Do not fail to separate calcium supplements and antacids from iron doses—this is the most common cause of treatment failure due to reduced absorption. 2
• Do not discontinue treatment prematurely once hemoglobin normalizes; continue at maintenance dose (30 mg daily) to replenish iron stores. 1, 2
• Do not overlook dietary counseling about iron-rich foods and absorption enhancers, as this improves overall iron status. 1, 2
• Be aware that hemoglobin >15.0 g/dL or hematocrit >45.0% in second or third trimester may indicate poor blood volume expansion and potential pregnancy complications—evaluate further. 1