Hemolytic Disease of the Newborn (HDN)

What is hemolytic disease of the newborn?

Hemolytic disease of the newborn (HDN) is a blood problem in newborn babies. It occurs when your baby's red blood cells break down at a fast rate. It’s also called erythroblastosis fetalis. 

• Hemolytic means breaking down of red blood cells.

• Erythroblastosis means making immature red blood cells.

• Fetalis means fetus.

What causes HDN in a newborn?

All people have a blood type (A, B, AB, or O). Everyone also has an Rh factor (positive or negative). There can be a problem if a mother and baby have a different blood type and Rh factor.

HDN happens most often when an Rh negative mother has a baby with an Rh positive father. If the baby's Rh factor is positive, like their father's, this can be an issue if the baby's red blood cells cross to the Rh negative mother.

This often happens at birth when the placenta breaks away. But it may also happen any time the mother’s and baby's blood cells mix. This can occur during a miscarriage or fall. It may also happen during a prenatal test. These can include amniocentesis or chorionic villus sampling. These tests use a needle to take a sample of tissue. They may cause bleeding.

The Rh negative mother’s immune system sees the baby's Rh positive red blood cells as foreign. Your immune system responds by making antibodies to fight and destroy these foreign cells. Your immune system stores these antibodies in case these foreign cells come back again. This can happen in a future pregnancy. You are now Rh sensitized.

Rh sensitization normally isn’t a problem with a first pregnancy. Most problems occur in future pregnancies with another Rh positive baby. During that pregnancy, the mother's antibodies cross the placenta to fight the Rh positive cells in the baby's body. As the antibodies destroy the cells, the baby gets sick. This is called erythroblastosis fetalis during pregnancy. Once the baby is born, it’s called HDN.

Which children are at risk for HDN?

The following can raise your risk for having a baby with HDN:

• You’re Rh negative and have an Rh positive baby but haven’t received treatment.

• You’re Rh negative and have been sensitized. This can happen in a past pregnancy with an Rh positive baby. Or it can happen because of an injury or test in this pregnancy with an Rh positive baby. 

HDN is about 3 times more common in white babies than in African-American babies.

What are the symptoms of HDN in a newborn?

Symptoms can occur a bit differently in each pregnancy and child.

During pregnancy, you won't notice any symptoms. But your healthcare provider may see the following during a prenatal test:

• A yellow coloring of amniotic fluid. This color may be because of bilirubin. This is a substance that forms as blood cells break down.

• Your baby may have a big liver, spleen, or heart. There may also be extra fluid in their stomach, lungs, or scalp. These are signs of hydrops fetalis. This condition causes severe swelling (edema).

After birth, symptoms in your baby may include:

• Pale-looking skin. This is from having too few red blood cells (anemia).

• Yellow coloring of your baby’s umbilical cord, skin, and the whites of their eyes (jaundice). Your baby may not look yellow right after birth. But jaundice can come on quickly. It often starts in 24 to 36 hours.  

• Your newborn may have a big liver and spleen.

• A newborn with hydrops fetalis may have severe swelling of their entire body. They may also be very pale and have trouble breathing.

How is HDN diagnosed in a newborn?

HDN can cause symptoms similar to those caused by other conditions. To make a diagnosis, your child’s healthcare provider will look for blood types that cannot work together. Sometimes this diagnosis is made during pregnancy. It will be based on results from the following tests:

• Blood test. Testing is done to look for Rh positive antibodies in your blood.

• Ultrasound. This test can show enlarged organs or fluid buildup in your baby.

• Amniocentesis. This test is done to check the amount of bilirubin in the amniotic fluid. In this test, a needle is put into your abdominal and uterine wall. It goes through to the amniotic sac. The needle takes a sample of amniotic fluid.

• Percutaneous umbilical cord blood sampling. This test is also called fetal blood sampling. In this test, a blood sample is taken from your baby’s umbilical cord. Your child’s healthcare provider will check this blood for antibodies, bilirubin, and anemia. This is done to check if your baby needs an intrauterine blood transfusion.

The following tests are used to diagnose HDN after your baby is born:

• Testing of your baby's umbilical cord. This can show your baby’s blood group, Rh factor, red blood cell count, and antibodies.

• Testing of the baby's blood for bilirubin levels.

How is HDN treated in a newborn?

During pregnancy, treatment for HDN may include the following.

What are possible complications of HDN in a newborn?

When your antibodies attack your baby’s red blood cells, they are broken down and destroyed (hemolysis).

When your baby’s red blood cells break down, bilirubin is formed. It’s hard for babies to get rid of bilirubin. It can build up in their blood, tissues, and fluids. This is called hyperbilirubinemia. Bilirubin makes a baby’s skin, eyes, and other tissues to turn yellow. This is called jaundice.

When red blood cells breakdown, this makes your baby anemic. Anemia is dangerous. In anemia, your baby’s blood makes more red blood cells very quickly. This happens in the bone marrow, liver, and spleen. This causes these organs to get bigger. The new red blood cells are often immature and can’t do the work of mature red blood cells.

Complications of HDN can be mild or severe.

During pregnancy, your baby may have the following:

• Mild anemia, hyperbilirubinemia, and jaundice. The placenta gets rid of some bilirubin. But it can’t remove all of it.

• Severe anemia. This can cause your baby’s liver and spleen to get too big. This can also affect other organs.

• Hydrops fetalis. This happens when your baby's organs aren’t able to handle the anemia. Your baby’s heart will start to fail. This will cause large amounts of fluid buildup in your baby's tissues and organs. Babies with this condition are at risk for being stillborn.

After birth, your baby may have the following:

• Severe hyperbilirubinemia and jaundice. Your baby’s liver can’t handle the large amount of bilirubin. This causes your baby’s liver to grow too big. They will still have anemia.

• Kernicterus. This is the most severe form of hyperbilirubinemia. It’s because of the buildup of bilirubin in your baby’s brain. This can cause seizures, brain damage, and deafness. It can even cause death.

What can I do to prevent hemolytic disease of the newborn?

HDN can be prevented. Almost all women will have a blood test to learn their blood type early in pregnancy.

If you’re Rh negative and have not been sensitized, you’ll get a medicine called Rh immunoglobulin (RhoGAM). This medicine can stop your antibodies from reacting to your baby’s Rh positive cells. Many women get RhoGAM around week 28 of pregnancy.

If your baby is Rh positive, you’ll get a second dose of medicine within 72 hours of giving birth. If your baby is Rh negative, you won’t need a second dose

Key points about hemolytic disease of the newborn

• HDN occurs when your baby's red blood cells break down at a fast rate.

• HDN happens when an Rh negative mother has a baby with an Rh positive father.

• If the Rh negative mother has been sensitized to Rh positive blood, her immune system will make antibodies to attack her baby.

• When the antibodies enter the baby's blood, they will attack the red blood cells. This causes them to break down. This can cause problems.

• This condition can be prevented. Women who are Rh negative and haven’t been sensitized can receive medicine. This medicine can stop your antibodies from reacting to your baby’s Rh positive cells.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

• Know the reason for the visit and what you want to happen.

• Before your visit, write down questions you want answered.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.

• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.

• Ask if your child’s condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if your child does not take the medicine or have the test or procedure.

• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.