Hemolytic Disease of the Fetus and Newborn




Hemolytic disease of the fetus and newborn (HDFN) is a blood disorder that causes your baby’s red blood cells to break down quickly. When red blood cells break down it is called hemolysis. Hemolysis causes anemia (low number of red blood cells) and jaundice (an increased bilirubin level) during the first few days to weeks of your baby’s life. Severe anemia can cause critical illness since it is harder to deliver oxygen throughout the body. This type of severe jaundice can lead to hearing problems/deafness and brain damage if left untreated. HDFN occurs when there is a mismatch between the mother’s and baby’s blood type and/or Rh factor during pregnancy.


Everyone has a blood type (A, B, AB, O), and Rh factor (Rh-positive or Rh-negative), as well as many other unique proteins, on the surface of the red blood cells. HDFN occurs when there is a mismatch (incompatibility) between the mother’s and baby’s blood type and/or Rh factor. That is why you may hear HDFN called Rh incompatibility or ABO incompatibility.  Rh incompatibility generally requires more monitoring and treatment than ABO incompatibility.  Less commonly, there are other mismatches, with antibodies directed against other blood groups, resulting in HDFN. The mismatch can happen when the mother’s blood mixes with the baby’s blood at birth, when the placenta breaks away, during a miscarriage, or during a prenatal test. When this happens, the mother’s immune system thinks the baby’s red blood cells are foreign. The mother’s blood develops antibodies against the baby’s red blood cells. Typically, HDFN does not occur with the mother’s first pregnancy. This is because the baby is born before many of the antibodies have developed. HDFN most often happens with future pregnancies when the mother’s antibodies that were made during a previous pregnancy are able to cross the placenta and destroy the baby’s red blood cells.


There are tests that can be done before your baby is born to check for HDFN:

  • Blood test – to see if the mother has antibodies against red blood cells
  • Anatomy Ultrasound – a high-resolution ultrasound to assess organs for any enlargement. When a fetus is anemic the organs can be enlarged.
  • Amniocentesis – a medical procedure in which a small amount of amniotic fluid is extracted and then studied in the lab to screen for genetic abnormalities


How is HDFN Treated Before Your Baby is Born?

If your baby is diagnosed with HDFN, you may have some or all of the below treatments depending on your condition:

  • Labs – this measures the strength of your red blood cell antibodies.
  • Ultrasound – This checks the blood flow within your baby’s veins.
  • Intrauterine blood transfusion – This gives your baby new red blood cells to prevent them from getting severe anemia. A needle is guided into a vein in the umbilical cord to give the blood directly to your baby.
  • Early delivery: This is done to prevent HDFN from worsening once the baby is big enough.

How is HDFN Treated After Your Baby is Born?

At the delivery hospital, a doctor who specializes in treating newborns (neonatologist) will be involved in your baby’s care. The neonatologist will assess your baby’s breathing and heart rate, and examine the baby for other problems.

  • Your baby may get care in your delivery hospital’s neonatal intensive care unit (NICU) or may be transferred to the Nationwide Children’s Hospital NICU.
  • Your baby will have blood tests done, including:
    • Blood type and Rh factor
    • Direct antiglobulin test (DAT)
      • This test checks to see if there are antibodies against red blood cells.
    • Complete blood count (CBC)
      • This test will measure your baby’s red blood cell (RBC) count to look for anemia. RBCs contain hemoglobin, which is an iron-rich protein that carries oxygen throughout our bodies.
    • Reticulocyte count
      • This test measures your baby’s production of new red blood cells. The reticulocyte count should be high when the hemoglobin is low. This means that the baby is making more red blood cells.
    • Bilirubin
      • This test measures how much bilirubin is in the blood. Bilirubin is a yellow substance made after red blood cells break down. It travels through the liver before it is removed by the body. In HDFN, the red blood cells are being destroyed quickly. This means that your baby can develop jaundice, or a yellow appearance to the skin.