Rh Incompatibility
What is Rh Incompatibility?
Rh incompatibility is a condition that occurs when two different Rh blood types mix. The Rh factor is a protein found on the surface of red blood cells. People who have this protein are Rh positive. People who do not have it are Rh negative.
This condition most commonly affects pregnancy. When an Rh-negative mother carries an Rh-positive baby, her immune system may see the baby's blood cells as foreign. Her body can then produce antibodies that attack the baby's red blood cells. This immune response can cause serious health problems for the baby.
Rh incompatibility can also happen during blood transfusions. If an Rh-negative person receives Rh-positive blood, their body creates antibodies against the Rh antigen. A second exposure to Rh-positive blood can trigger a severe immune reaction. Knowing your Rh type helps prevent these complications.
Symptoms
- In babies, yellowing of the skin and eyes, also called jaundice
- Severe anemia in newborns, which means low red blood cell count
- Enlarged liver or spleen in affected infants
- Fluid buildup in the baby's body tissues
- Heart failure in severe cases of fetal anemia
- Stillbirth or death shortly after birth in untreated cases
- In adults receiving incompatible transfusions, fever and chills
- Dark-colored urine after transfusion reaction
- Back pain and breathing difficulty during transfusion reactions
Most Rh-negative pregnant women have no symptoms during their first pregnancy with an Rh-positive baby. The problems typically develop in later pregnancies if the condition is not prevented.
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Causes and risk factors
Rh incompatibility happens when Rh-negative and Rh-positive blood types come into contact. During pregnancy, this occurs when an Rh-negative mother becomes pregnant with an Rh-positive baby. The baby inherits the Rh-positive factor from the father. Small amounts of the baby's blood can cross the placenta into the mother's bloodstream during pregnancy or delivery. This triggers the mother's immune system to make antibodies against Rh-positive cells.
Risk factors include having Rh-negative blood type while carrying an Rh-positive baby. Previous pregnancies, miscarriages, or abortions increase risk if sensitization occurred. Medical procedures like amniocentesis can cause blood mixing. Abdominal trauma during pregnancy raises the risk. Blood transfusions with incompatible Rh types also cause this condition. The risk is highest in second and later pregnancies if preventive treatment was not given.
How it's diagnosed
Rh incompatibility is diagnosed through blood tests that identify your Rh type. Antigen typing tests determine whether you have Rh-positive or Rh-negative blood. All pregnant women receive Rh typing early in prenatal care. If a woman is Rh negative, additional antibody screening tests check whether she has already developed antibodies against Rh-positive blood.
Rite Aid offers Rh type testing through our antigen typing add-on test at Quest Diagnostics locations nationwide. Knowing your Rh status is essential for pregnancy planning and safe blood transfusions. Your doctor may also test the baby's father to determine if the baby might be Rh positive. Regular monitoring throughout pregnancy helps catch any problems early.
Treatment options
- Rh immunoglobulin injections, also called RhoGAM, given during pregnancy and after delivery
- Preventive RhoGAM shots at 28 weeks of pregnancy for Rh-negative mothers
- RhoGAM within 72 hours after delivery, miscarriage, or abortion
- Close monitoring of baby's health through ultrasound and blood flow studies
- Intrauterine blood transfusions for severely affected babies before birth
- Early delivery if the baby shows signs of severe anemia
- Phototherapy, or light therapy, to treat jaundice in newborns
- Exchange transfusions to replace the baby's blood if anemia is severe
- Intravenous immunoglobulin to reduce antibody effects in some cases
Need testing for Rh Incompatibility? Add it to your panel.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Rh incompatibility occurs when Rh-negative and Rh-positive blood types mix, usually during pregnancy or blood transfusion. The Rh factor is a protein on red blood cells. When an Rh-negative person is exposed to Rh-positive blood, their immune system creates antibodies that attack Rh-positive cells. This can cause serious health problems, especially for babies during pregnancy.
Rh-negative women carrying Rh-positive babies are at highest risk. About 15% of people are Rh negative. The risk increases with each pregnancy if preventive treatment is not given. Anyone receiving a blood transfusion needs Rh-compatible blood to avoid this condition.
Blood tests identify your Rh type and check for antibodies. All pregnant women receive Rh typing during early prenatal care. If you are Rh negative, your doctor will test for antibodies that show whether you have been sensitized. These simple blood tests are done at the start of pregnancy and throughout prenatal care.
Yes, Rh incompatibility is highly preventable with RhoGAM injections. Rh-negative mothers receive RhoGAM at 28 weeks of pregnancy and within 72 hours after delivery. RhoGAM is also given after miscarriage, abortion, or prenatal procedures. These shots prevent the mother's body from making antibodies against Rh-positive blood.
Untreated Rh incompatibility can cause severe anemia in babies, leading to jaundice, heart failure, or brain damage. In the most serious cases, babies can experience stillbirth or death shortly after birth. Each subsequent pregnancy typically has worse effects if prevention is not used. Modern treatment with RhoGAM has made these severe outcomes rare.
The first pregnancy usually has minimal effects because the mother has not yet developed antibodies. Sensitization typically occurs during delivery when the baby's blood enters the mother's bloodstream. Later pregnancies are at higher risk if RhoGAM was not given. This is why preventive treatment during the first pregnancy is so important.
Treatment includes RhoGAM injections to prevent antibody formation and close monitoring of the baby's health. Doctors use ultrasound and special blood flow studies to check for anemia. If the baby develops severe anemia before birth, intrauterine blood transfusions may be needed. Some babies require early delivery and treatment with phototherapy or exchange transfusions after birth.
Men do not experience pregnancy-related Rh incompatibility, but they can have transfusion reactions. If an Rh-negative man receives Rh-positive blood, his body will create antibodies. A second exposure can cause a severe immune reaction with fever, chills, and organ damage. Knowing your Rh type ensures you receive compatible blood during transfusions.
Yes, RhoGAM is very safe and has been used for over 50 years. It contains antibodies that prevent the mother's immune system from reacting to Rh-positive blood. RhoGAM does not harm the baby or affect future fertility. The benefits of preventing Rh incompatibility far outweigh any minimal risks.
All pregnant women should have Rh typing at their first prenatal visit. Rh-negative women need antibody screening tests throughout pregnancy to check for sensitization. Testing is typically done in the first trimester and again around 28 weeks. Additional tests may be needed after delivery, miscarriage, or any event that could cause blood mixing.