Rh Incompatibility

One of the first prenatal tests your doctor will give you is a blood test to see if you are Rh negative or positive. Depending on the results, you and your baby may just not get along.

Rh Factor

The Rh factor (Rhesus factor) is an antigen or protein that is on the surface of red blood cells. It was named after the monkeys in which it was first discovered. Those people with Rh factor are Rh-positive while those without it are, of course, Rh-negative. In cases of Rh incompatibility, a baby's red blood cells have a substance called the Rh D factor, and the mother's blood cells do not. In medical terms, the baby is Rh positive and the mother is Rh negative. If some of the baby's red blood cells leak into your system, your body may produce antibodies to the Rh D factor (a condition called sensitization). These antibodies can cross the placenta and destroy the red blood cells in your unborn baby or in the next Rh-positive baby you have.

Rh Incompatibility

Rh incompatibility happens only in cases where the mother is Rh negative and the baby is Rh positive. It does not happen if the Rh factor is the other way around. As a rule, you are not exposed to your baby's blood until you give birth, which usually means that the first birth is fine and the baby is not affected. During delivery, large amounts of the baby's blood often leak into the mother and if you are Rh negative, the next Rh positive baby you give birth to may have problems if you've developed antibodies against the Rh factor.

There are a few ways some of the baby's blood may leak into your system during your pregnancy:

· After an invasive procedure such as amniocentesis

· During an abortion or miscarriage

· If there is an ectopic pregnancy

· Heavy bleeding during pregnancy

Antibodies in an Rh negative woman can also develop as a result of having had an Rh positive blood transfusion. This, too, can cause incompatibility. Often sensitization can be prevented. However, if antibodies are formed they can cross the placenta and damage the blood cells of the Rh positive baby.

Signs & Symptoms

You will have no symptoms of Rh incompatibility. Symptoms and signs of the problem are seen in the baby if he or she develops hemolytic disease, an excess of bilirubin, a chemical made in the baby's liver. In this condition, the baby's red blood cells start to break down, causing anemia. The baby may

 have other problems due to the anemia, such as jaundice and, after birth, breathing problems. In severe cases, the unborn baby's blood cannot carry oxygen and the baby dies of heart failure. Miscarriages and stillbirths can also be attributed to Rh incompatibility. Not all of the news is bad, though. Some Rh positive babies born to Rh negative mothers are either healthy or have mild anemia that is easily treated. Administering a vaccine-like injection of Rh known as a RhoGAM can help avoid these problems.

RhoGAM Injection

RhoGAM, or Rh-immune globulin, is an injection given to Rh negative women during their 28th week of pregnancy and then again within 72 hours of birth, miscarriage, amniocentesis or chorionic villus sampling. This injection contains antibodies that will help kill off any of your baby's red blood cells that may have entered your blood stream, thereby preventing your body from developing its own antibodies to your baby's blood. While RhoGAM will help you to avoid Rh problems in future pregnancies, it will be necessary to receive RhoGAM in all your pregnancies. 


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