Rh-sensitization

Fetomaternal hemorrhage (FMH), which can occur during pregnancy or delivery, triggers an Rh-negative mother's immune system to develop antibodies against the antigens in her baby's blood if Rh-positive (occurring in about 60% of pregnancies involving Rh-negative mothers). This is called Rh-sensitization or alloimmunization. While this is the most common cause for Rh-sensitization, there are other ways in which sensitization can occur. For instance, Rh-sensitization can also occur when someone with Rh-negative blood receives a transfusion of Rh-positive blood or blood components, such as platelets.

While the placenta-cell layer (trophoblast) usually prevents the fetus's blood from entering the mother's bloodstream, certain conditions can create FMH. The resulting Rh-sensitization can occur during any of these events:

  • Delivery
  • Miscarriage
  • Amniocentesis
  • Chorionic villus sampling
  • Placental abruption
  • Manual extraction of placenta
  • External version (breech repositioning)
  • Abortion

Typically, only a small number of antibodies are produced in the first pregnancy. During delivery, however, the mother's immune system becomes sensitized to the Rh factor. In subsequent pregnancies, the mother produces a greater number of antibodies, which can cross the placenta to destroy the fetal red blood cells and create significant health risks for the baby. With each subsequent Rh-positive pregnancy, the mother's antibody reaction is faster, with potentially more severe consequences.

An Rh-negative mother needs to receive anti-D IgG treatment during her first pregnancy and immediately following delivery to prevent Rh-sensitization that could endanger an Rh-positive fetus, particularly in future preganancies.

  1. Zipursky A, Paul V. The global burden of Rh disease. Arch Dis Child Fetal Ed. March 2011 Vol 96 No 2: F84-85.
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Important Safety Information

Rhophylac®, Rho(D) Immune Globulin Intravenous (Human), is a blood-derived injection given to women with an Rh-negative who might have an incompatible pregnancy—that is, who may be carrying an unborn child with Rh-positive blood. If a woman in such a pregnancy is not treated, the result could be “isoimmunization,” a condition in which the mother’s Rh-negative blood produces antibodies that could attack the unborn child’s Rh-positive blood cells, potentially creating serious health problems for the unborn child and any future children of the mother.

Rhophylac is given by physicians as routine protection against immunization, typically as administration during pregnancy, often with readministration within 72 hours following childbirth. It is also given in cases of obstetric complications, invasive procedures during pregnancies, incomplete pregnancies, and obstetric manipulative procedures in certain non-pregnant women. Rhophylac is also used in Rh-negative individuals who have received blood components containg Rh(D)-positive red blood cells. For suppression of Rh isoimmunization, Rhophylac can be administered intravenously or intramuscularly, but must not be given to newborn infant.

You should not receive Rhophylac if you have had a previous serious allergic reaction to Rhophylac or other human blood products. It should not be given if your blood has an insufficient quantity of a protein called IgA, has produced antibodies to IgA, or you have known hypersensititivy to IgA. Your physician will do a blood test to assess your situation regarding IgA.

Some women have experienced mild and temporary actions after receiving Rhophylac, such as fever; overall discomfort or uneasiness; headache; skin reactions (like hives or welts); and chills. If you received Rhophylac as a shot (intramuscularly), you could experience pain or tenderness at the injection site. Adverse reactions to Rhophylac typically do not last long. Discuss with your doctor any reaction or symptom you experience after administration of Rhophylac that concerns you.

Rhophylac is made from donated human blood. The risk of transmission of infections agents, including viruses, cannot be completely eliminated.

Immunoglobulin administration can transiently interfere with your response to live vaccines, such as measles, mumps and rubella. (Note that most influenza vaccines are not “live” vaccines.) Tell your doctor if you plan to receive a vaccine after receiving Rhophylac.

Please see full prescribing information for Rhophylac, which includes a boxed warning that does not apply to use of Rhophylac in pregnancy or in cases of incompatible transfusions.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

You can also report side effects to CSL Behring’s Pharmacovigilance Department at 1-866-915-6958.


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