In pregnancies at risk of fetal and neonatal alloimmune thrombocytopenia (FNAIT), intravenous immunoglobulin (IVIG) is often administered to the pregnant mother. It is a non-invasive treatment option that has been shown to contribute to improved outcomes for fetuses affected by FNAIT.
What is FNAIT?
Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is a rare but serious condition that affects 0.1% of pregnancies in which a pregnant mother’s immune system produces antibodies against the platelets of her fetus. This occurs when a fetus inherits platelet antigens from the father that are not compatible with the mother, typically involving a protein called human platelet antigen (HPA). The mother’s immune system recognizes the fetal platelets as foreign, attacking and destroying them, leading to low platelet levels (thrombocytopenia) in the fetus or newborn. FNAIT can result in complications such as bruising, bleeding under the skin and bleeding in organs such as the brain, which may lead to long-term neurological issues or, in severe cases, be life-threatening.
What is intravenous immunoglobulin therapy?
Intravenous immunoglobulin (IVIG) is pooled antibody plasma derived from anonymous donors that is used to help boost the immune systems of people affected by infectious, inflammatory or autoimmune conditions, such as FNAIT.
In pregnancies at risk of FNAIT, IVIG is often administered on a weekly basis from as early as 12 weeks gestation as a preventative measure to avoid or delay fetal bleeding. However, its use is off-label, and whether there are long-term effects for the baby requires further research.
Learn more about FNAIT causes and risk factors
While the exact mechanism of action of IVIG remains unknown, it works to block the mother’s immune system from attacking her baby’s blood platelets. It is a non-invasive therapy with no identified risk to the fetus. In comparison, intrauterine platelet transfusions (IUPT) are an invasive procedure, which increase the risk for fetal bleeding and potentially, miscarriage.
IVIG is often administered multiple times, as its purpose is to continually block the mother’s immune system from attacking the fetus. It may be administered either in a few large doses or in smaller doses on a more regular schedule.
The risks and side effects of IVIG
The most commonly reported side effects of IVIG are usually mild and include headache, fatigue, fever and chills. Moderate adverse events may include nausea, vomiting and chest pain. Rare serious reactions can occur in older patients with other existing conditions. These are most often related to the transfusion rate, which can be slowed to reduce symptoms.
Administering IVIG in pregnancies at risk of FNAIT often contributes to better outcomes for the baby, by helping to prevent bleeding and hemorrhage in the fetus. It also reduces the risk of miscarriage and severe complications such as ICH.
