Rh disease, or Rh incompatibility, occurs when the mother’s body attacks the blood cells within the developing fetus because their blood types are different. This can harm the child during pregnancy and/or after delivery.

The mother’s immune system considers the baby’s blood cells, which have a different blood type, as foreign. Therefore, the mother’s body becomes “sensitized” to those different blood cells and produces a protein called an “antibody”. These antibodies can then potentially destroy the child’s blood cells.

Mothers who have a blood type called “Rh-negative” are at risk if they are pregnant with a child with the Rh-positive blood type. This risk of Rh disease goes up after each pregnancy, after ectopic pregnancy, abortion, or miscarriage, and after certain tests done during pregnancy, such as amniocentesis.

A mother can become “sensitized” to the different blood type due to blood transfusion, bone marrow transplantation, or through an accidental needle stick injury.

A simple blood test can check for your Rh type. It is either positive or negative, and both are considered normal. However, only Rh-negative mothers are at risk for this disease.

The symptoms of Rh disease can be very different depending on how severe the disease is. It can cause jaundice, where the fetus’ or newborn’s skin and eyes turn yellow. It can also cause anemia, which is when the child doesn’t have the normal amount of blood cells because the mother’s body is destroying them. In severe cases, it can even cause brain damage, heart failure, and death.

If you know that you are Rh-negative, or have had a prior pregnancy affected by Rh disease, you may be at risk for Rh disease. Your doctor may want to do an antibody test; this blood test measures whether or not your body has already made an antibody to the Rh blood group.  Additionally, they may do an amniocentesis, to collect a sample of the fluid that surrounds the fetus. They may also do an ultrasound during pregnancy or test the DNA of the baby by another type of blood test.

They may test the biological father’s blood type to determine whether the child may be at risk.

No. Rh disease is due to a genetic difference in blood type between you and your partner, and your Rh type is entirely inherited from your parents.

As the parent, aside from complications from a potential miscarriage, there is little or no risk to you. The risk is primarily to the child.

Treatment mainly focuses on prevention. If a mother is at risk, then a drug called Rh immunoglobulin will be used. It is a shot, typically given twice during pregnancy, which can help prevent harm to the baby. However, it only works if the mother’s body has not already begun attacking the child’s blood cells. 

It is given once at about 28 weeks of pregnancy (6.5 months), and again shortly after the birth of the baby (within 72 hours). It may also need to be given during pregnancy in case of bleeding, trauma, miscarriage, ectopic pregnancy, abortion, or invasive procedures, like amniocentesis or fetal blood sampling. 

If the mother has already been sensitized, then prevention with Rh immunoglobulin will not work. Instead, treatment will depend on the severity of the Rh disease. Mild cases may only require simple monitoring. However, more severe cases may require additional treatment, which can include blood transfusion, supplements to help the baby produce more blood cells, and early delivery.

Because it takes the body some time to complete the process of creating antibodies against Rh-positive blood cells, the first pregnancy of an Rh-negative woman with an Rh-positive child is not likely to lead to Rh disease. However, future pregnancies with an Rh-positive child are at increasing risk.