What are the management recommendations for a pregnant woman with thalassemia minor?

Management of Thalassemia Minor in Pregnancy

Pregnant women with thalassemia minor should receive low-dose iron supplementation (30 mg/day) starting at the first prenatal visit, but avoid therapeutic iron doses unless true iron deficiency is confirmed, as their anemia is genetic and will not respond to iron therapy. 1

Initial Assessment and Screening

• Screen for anemia at the first prenatal visit using hemoglobin concentration or hematocrit, applying pregnancy-specific anemia criteria for each trimester 1
• Recognize that women of Mediterranean, African, or Southeast Asian ancestry with mild anemia unresponsive to iron therapy likely have thalassemia minor rather than iron deficiency 1
• Perform partner screening and genetic counseling to assess risk of thalassemia major in the fetus, as prenatal diagnosis can be achieved in early gestation 2
• Obtain baseline complete blood count, MCV, RDW, and serum ferritin to distinguish thalassemia minor from iron deficiency anemia 1

Iron Supplementation Strategy

• Start with prophylactic low-dose iron (30 mg/day) at the first prenatal visit, not therapeutic doses 1
• Do not escalate to therapeutic iron doses (60-120 mg/day) in thalassemia minor patients, as their anemia will not respond to iron therapy 1
• If anemia fails to respond after 4 weeks of iron supplementation despite compliance, perform further evaluation with MCV, RDW, and serum ferritin to confirm thalassemia minor diagnosis 1
• Avoid unnecessary IV iron administration in iron-replete patients, as 46% of IV iron in thalassemia minor pregnancies is given inappropriately to patients who are already iron-replete 3

Monitoring During Pregnancy

• Expect hemoglobin and hematocrit to be significantly lower throughout all three trimesters and postpartum compared to healthy pregnant women 4
• Anticipate that 31% of thalassemia minor patients will have hemoglobin <9 g/dL during the third trimester, though only 7.6% at delivery 3
• Monitor for worsening anemia, as thalassemia minor is associated with high rates of progressive anemia during pregnancy 3
• Screen aggressively for gestational diabetes, preeclampsia, and hypertension, though recent evidence suggests GDM risk may not be significantly elevated 4, 5

Key Clinical Pitfalls to Avoid

• The most common error is treating thalassemia minor anemia with therapeutic iron doses (60-120 mg/day), which provides no benefit and may cause iron overload 1
• Do not refer for further evaluation solely based on mild anemia if the patient has confirmed thalassemia minor and hemoglobin remains >9 g/dL 1
• Only refer to a physician familiar with anemia in pregnancy if hemoglobin falls below 9.0 g/dL or hematocrit below 27.0% 1

Postpartum Management

• Screen for anemia at 4-6 weeks postpartum using nonpregnant anemia criteria 1
• Risk factors for postpartum anemia include anemia continued through third trimester, excessive blood loss during delivery (which occurs in 8.9% of thalassemia minor patients), and multiple births 1, 3
• Stop supplemental iron at delivery if no risk factors for iron deficiency are present 1
• Counsel on regular laboratory screening and multidisciplinary care for future pregnancies 4

Neonatal Considerations

• Neonates of mothers with thalassemia minor are more likely to experience postnatal jaundice and excessive weight loss, requiring close monitoring 4
• Provide genetic counseling regarding the child's thalassemia carrier status based on parental testing 2, 6