Newborns diagnosed with hemolytic disease of the fetus and newborn (HDFN) often experience symptoms of 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. 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., and immediate treatment is required to prevent these conditions from becoming life-threatening.
Regular blood tests to monitor bilirubinBilirubin A yellow substance produced when red blood cells break down. High bilirubin levels in newborns with HDFN can cause jaundice or, in severe cases, brain damage. levels, hemoglobin and reticulocyte counts are essential to successful neonatal HDFN care.
What is HDFN?
Hemolytic disease of the fetus and newborn (HDFN) is an immune-mediated red blood cell 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.
What blood work is required in HDFN and why?
Newborns with HDFN can experience symptoms that range from mild to severe, and their overall health may be iaffected by medical interventions during pregnancy and a premature birth. In addition to treatment, they require close monitoring.
Learn more about HDFN symptoms and risks
Following birth and confirmation of HDFN, your baby will likely have regular blood tests to monitor several different markers of health, including:
Bilirubin levels
HyperbilirubinemiaHyperbilirubinemia A common cause of jaundice, this refers to higher than normal bilirubin levels in the blood. or jaundice is common in newborns with HDFN. Bilirubin is produced in the blood when red blood cells break down. The first total serum bilirubin (TSB) test is taken from the umbilical cord following birth. If levels are high, bilirubin needs to be monitored through blood work every four to six hours in the first 24 hours of life. PhototherapyPhototherapy A treatment that uses special blue light to help newborns break down bilirubin and prevent kernicterus. is then required to bring down bilirubin levels and daily blood tests will determine whether or not the treatment is working.
Red blood cell count
During pregnancy, 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. attacked and progressively destroyed the baby’s red blood cells. A low red blood count leads to anemia and severe anemia can lead to heart failure and brain damage if left untreated. Daily blood tests will monitor if the baby’s red blood cells are still breaking down, or if they are stabilizing. A blood transfusion may be required to treat anemia. Blood tests will continue to track the efficacy of the transfusion. An increasing red blood cell count means the treatment is resolving the baby’s anemia.
Reticulocyte count
The reticulocyte count measures the immature red blood cells being produced by the bone marrow. This indicates the rate at which the baby is replacing the red blood cells destroyed by maternal antibodies.
Maternal antibodies
A direct antiglobulin testDirect antiglobulin test A blood test used to detect antibodies attached to red blood cells. It helps confirm HDFN in newborns. measures the level of maternal antibodies in the newborn’s blood and tracks them as they gradually decrease.
Expect regular testing in the first few days to weeks
In the first days of life, daily blood tests will monitor how these levels develop in the newborn with HDFN. When the baby is ready to be discharged from the hospital, your doctor may order weekly blood tests to continue to monitor bilirubin levels and red blood cell count, as a relapse in anemia is possible.
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