Intravenous immunoglobulin (IVIG) is often administered to pregnant women who are considered at-risk for fetal and neonatal alloimmune thrombocytopenia (FNAIT). IVIG remains the gold standard for preventing bleeding complications due to FNAIT.
IVIG is not a one-size-fits-all treatment: The number of infusions needed varies from person to person based on risk level and individual responses to treatment.
What is IVIG?
IVIG is a therapy containing immune system antibodies that is given through an infusion into the vein. The treatment is used for a number of conditions including autoimmune diseases and immunodeficiency.
Read more about FNAIT treatment and care
In pregnant patients at risk of developing FNAIT, IVIG stops the mother’s immune system from launching an attack against her baby’s platelets. Researchers are still unsure exactly how IVIG works in FNAIT, but it’s believed that the neonatal Fc receptor, a protein that helps carry maternal antibodies to the fetus, might be involved. The treatment is currently used off-label, meaning it has yet to be approved by the U.S. Food and Drug Administration for the disease.
Standard-risk pregnancies for FNAIT
In patients who are considered standard-risk for FNAIT, meaning they have no history of FNAIT-related brain bleeds in past pregnancies, guidelines recommend that IVIG infusions should begin at 20 weeks gestation, usually at a dose of 1 gram per kilogram of your body weight (g/kg). As long as there are no complications, IVIg therapy continues weekly until the baby is born.
Some studies have been done to assess whether IVIG is useful in standard-risk patients. Overall, these studies haven’t shown that IVIG significantly lowers the risk of brain bleeds, also called intracranial hemorrhage (ICH), in infants born to standard-risk mothers.
It’s possible that as more data is collected over time, fewer standard-risk patients will be prescribed IVIG therapy. IVIG usage could be reduced by 79% if standard-risk pregnancies are no longer treated with IVIG, which would save money and help alleviate worldwide shortages of the drug.
Pregnancies at risk of FNAIT
A person is considered high-risk for FNAIT if they had a previous pregnancy with FNAIT-related ICH. In very high-risk patients, the ICH occurred between 28 and 36 weeks gestation, and in extremely high-risk patients, the ICH occurred before 28 weeks gestation.
High-risk patients are usually given 1 g/kg IVIG weekly beginning at 12 to 16 weeks gestation. In very high-risk pregnancies, this dose can be doubled to 2 g/kg beginning at 20 weeks gestation, while in extremely high-risk patients, the dose can be doubled as early as 12 weeks gestation.
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