Hemolytic Disease of the Fetus and Newborn (HDFN)

Hemolytic disease of the fetus and newborn (HDFN) is a blood disorder that causes your baby’s red blood cells to break down quickly.

What is Hemolytic Disease of the Fetus and Newborn (HDFN)?

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.

What are the Symptoms Associated with HDFN?

  • pale skin
  • yellowing of the skin (jaundice) or eyes
  • very dark urine
  • increased fatigue or irritability
  • rapid heart rate
  • rapid breathing
  • poor feeding

What Causes HDFN?

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.

How is HDFN Diagnosed?

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.

What are the Possible Treatment Options?

Treatment will depend on your baby’s symptoms and lab results. Some include:

  • Phototherapy - Your baby will be placed under special lights that help the body remove extra bilirubin.
  • Intravenous (IV) fluids - These fluids help the body get rid of extra bilirubin and stay hydrated.
  • Intravenous immunoglobulin (IVIG) - This is a fluid that contains antibodies from blood donors. It helps keep your from baby from destroying their red blood cells. As a result, it should also help lower your baby’s bilirubin levels.
  • Blood transfusion – This is when your baby receives blood from another blood donor. This is done to treat sever anemia
  • Exchange transfusion - This procedure removes some of your baby’s blood that has a high bilirubin level and replaces it with blood that has a normal bilirubin level. This is typically only done at the Nationwide Children’s hospital NICU.

What are the Possible Problems and Complications?

When a baby is watched closely for signs and symptoms of hemolytic anemia and gets proper medical care, complications are rare in HDFN.

  • Hyperbilirubinemia and severe jaundice - High levels of bilirubin can result in hearing problems and brain damage, if left untreated.
  • Heart failure - Severe untreated anemia can lead to heart failure since the heart is not getting enough oxygen-rich hemoglobin.

Discharge Planning

If your baby has anemia or needs IVIG or a red blood cell transfusion, they will see the hematology department at Nationwide Children’s. The hematology team will assess your baby’s blood labs and symptoms once or twice a week to decide if a blood transfusion is needed.  

Some babies need many blood transfusions during the first couple of months. Talk to your hematology provider about this.

Your baby will still need regular follow-up appointments to measure growth, development and nutrition. You will want to find a local pediatrician to take care of the routine checkups, immunizations and health care provider visits.

Lifelong Considerations

HDFN is a temporary (short-term) condition. The antibodies that destroy the baby’s red blood cells are usually gone within the first 8 to 12 weeks of life. With the right medical care, there are not lifelong medical issues in babies with HDFN.

Future Pregnancies

Future pregnancies may be affected by HDFN. Your obstetrician or maternal-fetal-medicine specialist will review your records and check antibody levels to decide how to best keep you and your baby healthy. Testing on the father of the baby may help find out if this could be a problem for future pregnancies.