Can intravenous (IV) iron therapy stimulate early delivery in pregnant women with iron deficiency anemia?

IV Iron Therapy and Risk of Early Delivery in Pregnant Women

Intravenous (IV) iron therapy does not stimulate early delivery in pregnant women with iron deficiency anemia and is considered safe for use after the first trimester of pregnancy. 1

Safety of IV Iron During Pregnancy

IV iron therapy is generally considered safe and effective for pregnant women with iron deficiency anemia, particularly when:

• Oral iron is insufficient or not tolerated
• Used after the 13th week of gestation (first trimester)
• Administered according to standard protocols

According to expert consensus guidelines, administration of IV iron is generally avoided prior to the 13th week of gestation due to a lack of safety data, but all IV iron formulations have been shown to be safe and effective in pregnancy after this period 1.

Timing of Administration

• First trimester: IV iron is generally avoided due to limited safety data
• Second and third trimesters: IV iron is considered safe and effective
• Approximately 80% of fetal iron accrues in the last trimester of pregnancy by active placental transport from mother to fetus 1

Impact on Pregnancy Outcomes

Rather than stimulating early delivery, evidence suggests that treating iron deficiency anemia during pregnancy may actually have beneficial effects:

• A meta-analysis evaluating oral versus IV iron therapy in pregnant women with iron deficiency anemia found that IV iron was associated with a higher birth weight 1
• Maternal iron deficiency anemia has been associated with adverse neonatal outcomes, including increased risk of preterm birth and low birth weight 1

Administration Guidelines

When administering IV iron during pregnancy:

• No special fetal monitoring is required during or following IV iron administration 1
• All IV iron formulations have established safety profiles for pregnancy but should be used with caution and monitoring for potential hypersensitivity reactions 2
• The usual treatment dose is 60-120 mg of elemental iron per day 1

Potential Reactions to IV Iron

Most reactions to IV iron are not true allergic reactions but rather complement activation-related pseudo-allergy (CARPA), characterized by:

• Flushing, myalgias and/or arthralgias, back pain and/or chest pressure
• Usually self-limited and most often seen at the beginning of infusion
• Not life-threatening and can occur without prior sensitization 1

Clinical Considerations

• IV iron is indicated for pregnant women with moderate anemia (Hb 7-9.9 g/dL) who don't respond to oral iron 2
• IV iron can be administered as a single dose or divided doses depending on the formulation 3
• Newer formulations like ferumoxytol allow for complete replacement doses in 1-2 visits rather than the 4-7 visits required with older formulations like iron sucrose 3

Rare Adverse Events

While generally safe, rare adverse events have been reported:

• A case report documented rhabdomyolysis after a second dose of IV iron sucrose at 32 6/7 weeks of gestation 4
• Such severe reactions are extremely rare and should not deter appropriate treatment of iron deficiency anemia

In conclusion, IV iron therapy is a safe and effective treatment for iron deficiency anemia during pregnancy after the first trimester and does not stimulate early delivery. In fact, treating maternal iron deficiency anemia may help prevent adverse outcomes including preterm birth.