Rh disease occurs during pregnancy. It happens when the Rh factors in your blood and your baby's blood don't match. It may also happen if you and your baby have different blood types.

Each person has a blood type (O, A, B, or AB). Everyone also has an Rh factor (positive or negative).

The Rh factor is a protein on the covering of the red blood cells. If the Rh factor protein is on the cells, the person is Rh positive. If there's no Rh factor protein, the person is Rh negative.

A baby may have the blood type and Rh factor of either parent, or a combination of both parents.

There can be a problem if you are Rh negative and you have a baby with someone who is Rh positive. If your baby's Rh factor is positive, it can be an issue if your baby's red blood cells cross to you. When that happens, you become sensitized to Rh positive blood. This means you make an immune response or antibodies to the Rh D antigen.

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

When you are Rh negative, your immune system sees your 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. It can happen in a future pregnancy. You are now Rh sensitized.

Rh sensitization normally isn't a problem with a first pregnancy. Most issues occur in future pregnancies with another Rh-positive baby. During that pregnancy, your antibodies cross the placenta to fight the Rh-positive cells in your baby's body. As the antibodies destroy the cells, your baby gets sick. Your baby could have jaundice, heart failure, and enlarged organs.

People who are Rh negative and are pregnant with a baby whose other parent is Rh positive are at risk for this condition. Your risk is much higher if you've been pregnant before. There is normally no risk for Rh disease during a first pregnancy, unless you've been sensitized before pregnancy.

You will have no signs of Rh disease. But your baby can have problems if you develop antibodies.

Symptoms can occur a bit differently in each pregnancy and child. During pregnancy, symptoms may include:

• A yellow coloring of amniotic fluid. This color may be because of bilirubin. This is a substance that is released when blood cells break down.
• Your baby may have a big liver, spleen, or heart. There may also be extra fluid in your baby's stomach, lungs, or scalp. These are signs of hydrops fetalis. This condition causes severe swelling (edema).

Rh disease can cause problems in your newborn. The condition caused by Rh disease in babies is called hemolytic disease of the newborn. Your baby may have the following symptoms:

• Yellow coloring of the skin and whites of the eyes (jaundice).
• Pale-coloring because of anemia.
• Fast heart rate (tachycardia).
• Fast breathing (tachypnea).
• Lack of energy.
• Swelling under the skin.
• Large belly (abdomen)

These symptoms can be caused by other conditions. See your doctor for a diagnosis.

Your doctor may suspect Rh disease if you had an Rh positive baby in a past pregnancy. Your doctor will ask you about your health history. Your doctor will also give you an exam.

You may need the following tests to check for Rh disease:

• Blood tests. These check for Rh positive antibodies in your blood.
• Ultrasound. This test can show enlarged organs or fluid buildup in your baby. Measurement of the speed of the blood flow in the baby's main artery in the brain can predict the presence of fetal anemia.
• Amniocentesis. This test checks the amount of bilirubin in the amniotic fluid. In this test, a needle is inserted 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 or fetal blood sampling. In this test, a blood sample is taken from your baby's umbilical cord. Your doctor will check this blood for antibodies, bilirubin, and anemia.

Treatment will depend on your pregnancy and general health. It will also depend on how severe the condition is.

This test puts red blood cells into your baby's circulation. In this test, a needle is placed through your uterus. It goes into your baby's abdominal cavity to a vein in the umbilical cord. Your baby may need sedative medicine to keep from moving. You may need to have more than one transfusion.

If your baby gets certain complications, your baby may need to be born early. Your doctor may induce labor once your baby has mature lungs.

Complications from Rh disease in your baby may include:

• Anemia. In some cases, anemia is severe. Your baby's spleen and liver may be enlarged.
• Jaundice.
• Hydrops fetalis. This condition happens when your baby's organs aren't able to handle the anemia. Your baby's heart will start to fail. That 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 jaundice. Your baby's liver can't handle the large amount of bilirubin. So your baby's liver grows too big. Your baby will still have anemia.
• Kernicterus. This condition is the most severe form of too much bilirubin. It's due to the buildup of bilirubin in your baby's brain. It can cause seizures, brain damage, and deafness. It can even cause death.

Rh disease can be prevented. All people will have a blood test to learn their blood type early in pregnancy.

If you are 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. You'll get RhoGAM around week 28 of pregnancy. You may get it earlier if you have vaginal bleeding, trauma, or amniocentesis before 28 weeks.

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.

Contact your doctor if you're Rh negative and have vaginal bleeding or trauma during your pregnancy. Your doctor may give you RhoGAM.

• Rh disease occurs during pregnancy. It happens when the Rh factors in your blood and your baby's blood don't match.
• If you have been sensitized to Rh positive blood, your immune system will make antibodies to attack your baby.
• When the antibodies enter your baby's bloodstream, they will attack the red blood cells, causing them to break down. This can lead to problems.
• This condition can be prevented. People 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.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new directions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your 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 you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours or on weekends.