What is HDFN?
Hemolytic disease of the fetus and newborn (HDFN) is an immune-mediated red blood cell (RBC) disorder that occurs when a baby’s RBCs break down quickly, which is called hemolysis. HDFN is caused by a mismatch between a mother’s and her baby’s blood type (A, B, AB, or O) or Rhesus (RhRh factor A protein or antigen found on red blood cells. When an Rh-negative mother carries an Rh-positive fetus, her immune system may make antibodies that attack the fetus' red blood cells.) factor (Rh-positiveRh-Positive A blood type trait that means your red blood cells have the Rh(D) antigen. or Rh-negativeRh-Negative A blood type trait that means your red blood cells lack the Rh(D) antigen.) during pregnancy. Numerous antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. to RBC antigensAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. can be linked to HDFN, such as those from the ABO and Rh blood groupBlood group A classification of blood based on inherited markers found on red blood cells. The ABO and Rh blood groups are most common in HDFN. systems.
What can happen to a baby born with HDFN?
In HDFN, a baby’s RBCs break down quickly—a process called hemolysis. Certain maternal antibodies pass through the placenta and attack the fetal RBCs, which leads to the development of fetal anemia. The fetus’s RBCs begin to break down at a rapid rate, which is known as erythroblastosis fetalis. Several tests can be performed prior to a baby’s birth to check for the presence of HDFN.
HDFN does not affect the mother, but it can result in serious outcomes for the infant, including anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells., jaundiceJaundice A common symptom of HDFN, jaundice is caused by excess bilirubin and is characterized by a yellow tint to the skin or eyes., heart failure, brain damage and even death.
Current treatment of HDFN
Current treatment often includes administering Rh immunoglobulin (RhIgRho(D) immune globulin A preventive treatment that helps prevent Rh-negative mothers from developing antibodies that may harm the fetus.) to RhD-negative mothers throughout their pregnancy and shortly following the birth of an RhD-positive baby. Over the years, this method has decreased the rate of Rh-hemolytic disease. RhIg is injected into the mother to prevent severe fetal anemia from occurring in future pregnancies.
Treatment with RhIg cannot help if an Rh-negative mother has already produced antibodies. In such cases, the fetus will need to be checked throughout the pregnancy, usually with the use of ultrasound.
Read more about HDFN treatment and care
Can RhIg treatment interfere with vaccinations?
The administration of RhIg to an infant may interfere with the child’s immune response to certain routine live virus vaccines, including measles, mumps, and rubella (MMR) vaccination. Antibodies in the RhIg preparation may slow down a child’s response to a live vaccine.
Typically, children receive two doses of the MMR vaccine. The first dose usually is administered between 12 and 15 months of age, and the second dose is administered between four and six years of age.
Guidelines recommend that immunization with live vaccines should not be given within three months following RhIg administration. Appropriate ages for administering live vaccines to children who have been treated with RhIg are the same as those for children who did not receive such therapy, provided at least three months have elapsed since the administration of RhIg. Live vaccines include the following:
- MMR vaccine
- Oral polio vaccine
- Varicella (chickenpox) vaccine
- Rotavirus (a viral infection that can cause severe diarrhea and lead to dehydration) vaccine
- Intranasal influenza vaccine
Variations in guideline recommendations
If international travel with a baby is planned, these guidelines will need to be adjusted to a certain extent. Ultimately, you should consult with a trusted healthcare professional about what works best for your baby, given their medical needs and history.
