What is HDFN?
Hemolytic disease of the fetus and newborn (HDFN) is a rare red blood cell (RBC) disorder that occurs when there is a mismatch (incompatibility) between a mother’s and her baby’s blood type.
In HDFN, a pregnant woman’s antibodies—protective proteins generated by the immune system—pass through the placenta during pregnancy or at delivery. The incompatibility reported in HDFN causes the mother’s 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 attack the fetal or newborn antibodies. This can lead to hemolysis, anemia and jaundiceJaundice A common symptom of HDFN, jaundice is caused by excess bilirubin and is characterized by a yellow tint to the skin or eyes. (increased bilirubin levels).
When a baby is diagnosed with HDFN, the baby’s caregivers will be required to make decisions for the baby based on their healthcare provider’s advice and guidance.
The primary cause of HDFN
The mismatch in HDFN can occur between a mother’s and her baby’s blood type (A, B, AB or O). Each of these blood groups can be either Rhesus (Rh) factor positive or 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. negative. The most severe form of HDFN is often linked to Rh disease.
When a baby is conceived, 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. antigens are inherited from both the mother and the father. Most often, HDFN is caused by the D antigen, although other Rh 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 involved as well.
Read more about HDFN therapies
Rh disease generally takes place when a mother is RhD negative, her baby is RhD positive and the mother has developed an antibodyAntibody 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 RhD from having had a prior exposure to RhD-positive blood.
Difficulties arise when the mother’s blood type is negative (it does not contain a particular antigen) and her baby’s blood type is positive (it has inherited that particular antigen from the father). Rh disease is not usually reported in a woman’s first pregnancy because her immune system response is not yet sufficiently strong.
Changes in HDFN over recent decades
Following the introduction of anti–D immunoprophylaxis, HDFN linked to ABO incompatibility and other alloantibodies became a common cause of this disorder in Western countries.
The administration of Rh immunoglobulin to RhD-negative mothers throughout their pregnancy and then shortly following the birth of a D-positive infant has dramatically decreased the incidence of Rh-hemolytic disease.
Diagnosis of HDFN
Prior to giving birth, a mother can be evaluated for the presence of HDFN:
- Blood tests can be performed for Rh typing and reflex antibody screening
- Serial antibody level measurements and middle cerebral artery blood flow measurements can be obtained
- A high-resolution ultrasoundUltrasound An imaging test that uses sound waves to monitor fetal growth, development and signs of complications during pregnancy. can be performed to study the fetal organs for any enlargement
- Cell-free fetal DNA prenatal screening can be performed
- Amniocentesis can be performed, in which a small amount of amniotic fluid is collected and examined in the laboratory to screen for any abnormalities
HDFN treatment decisions prior to the baby’s birth
Certain treatments and procedures may be agreed upon between a patient’s caregivers and their healthcare providers prior to a mother giving birth.
Occasionally, an intrauterine intravascular blood transfusion can be performed, in which the baby receives new RBCs to prevent the development of severe 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..
Sometimes early delivery at 32 to 35 weeks is suggested, to prevent HDFN from worsening if the fetus is becoming too large. Early delivery also may be recommended when severe complications are present and the baby’s lungs are considered sufficiently mature to sustain the birth process.
HDFN treatment decisions following a baby’s birth
There are many possible ways to treat a baby that a parent, along with their healthcare providers, can decide on based on symptoms and laboratory test results:
- PhototherapyPhototherapy A treatment that uses special blue light to help newborns break down bilirubin and prevent kernicterus.
- Intravenous (IV) fluids for hydration
- IV immunoglobulinIntravenous immunoglobulin A therapy made from donated antibodies that may help reduce the mother’s immune response and protect the fetus. (IVIGIntravenous immunoglobulin A therapy made from donated antibodies that may help reduce the mother’s immune response and protect the fetus.)
- Blood transfusions for severe anemia
- Exchange transfusions
Ways to prevent HDFN
Prevention of HDFN entails the administration of Rho(d) immune globulin to Rh-negativeRh-Negative A blood type trait that means your red blood cells lack the Rh(D) antigen. mothers:
- At 28 weeks gestational age
- Within 72 hours of termination of a pregnancy
- Following the occurrence of any vaginal bleeding
- After amniocentesis
- Following chorionic villus sampling, which involves prenatal testing to diagnose certain genetic abnormalities and confirm the sex of the baby
The agreement is critical to the newborn’s well-being.
HDFN is usually a short-term condition, with the antibodies that destroy the newborn’s RBCs usually disappearing in the initial eight to 12 weeks of life. When the appropriate medical care is received— which should be a joint decision by the mother and the father—no lifelong medical issues will exist in children with HDFN.
Because all future pregnancies may be impacted by HDFN, appropriate clinicians need to evaluate the future mother, check her antibody levels, and agree on the best ways in which to maintain the health of the mother and her baby. Evaluating the father can shed light on whether HDFN might be an issue in future pregnancies.
