Rh Negative Blood and Pregnancy

You are probably somewhat familiar with blood types. Your mom may have told you that you were O+ or B-, etc. Blood is grouped by type into A, B, AB, or O and also by the Rh factor, either negative or positive. Most people are Rh positive. This means they have an antigen on their red blood cells for the Rh factor. People without the Rh factor antigen are Rh negative.

So, How Is Being Rh Negative a Problem?

When Rh-negative blood is exposed to Rh-positive blood, the Rh negative person begins producing antibodies to fight the invading blood. Antigens trigger your body to produce antibodies. Antibodies are usually a good thing and serve to protect a person from foreign invaders.

The problem lies when a pregnant woman is carrying a baby that is Rh positive. If the mother has antibodies to the Rh antigen, those antibodies can attack the baby's red blood cells. This can lead to complications to the baby including anemia, jaundice, and other blood-related problems.

There is good news! Rh incompatibilities can be prevented and treated.


Part of the normal blood workup for the pregnant woman is testing for blood type and Rh factor. Her blood is also checked for the presence of Rh antibodies. If antibodies are present, the mother has already been exposed to RH positive blood at some point in her life and her body already has antibodies to the Rh factor. Treatment for Rh incompatibilities may be necessary.

Treatment of Rh Incompatibilities

If you already have antibodies for the Rh factor your doctor will want to monitor you and baby closely. If your baby is Rh negative, no treatment will be needed. (If both baby's mother and father have Rh-negative blood type, baby will be Rh negative, however Rh positive fathers can produce Rh negative or Rh positive babies.) If your baby is Rh positive, your doctor will have to run tests to monitor your baby's status. She may check your blood for antibody levels. She may also check your amniotic fluid for the breakdown of baby's red blood cells. The ultimate goal will be to hold off delivery until baby is mature at around 36-37 weeks, but it may be necessary to deliver baby early if baby shows signs of distress. Sometimes doctors will recommend an intrauterine transfusion for baby. As with all procedures, there are risks involved.

Thankfully with advancements in technology, Rh incompatibility is usually very preventable and treatable.

Rh negative

Prevention of Rh Incompatibilities

Rh factor incompatibility can be prevented by administration of the RhoGAM shot. Because baby's blood does not usually mix with the mother's until birth, first pregnancies usually have no risk for problems to baby. During birth, bits of the baby's blood will mix with the mother's blood. The RhoGAM shot should be given within 72 hours of birth. This shot will stop the mother from developing antibodies to the Rh factor. Because there is a slight risk of placental tears during the later part of pregnancy, the RhoGAM shot is often given at 28 weeks of pregnancy as well. If your baby's blood type is Rh negative, the RhoGAM shot is not necessary. The RhoGAM shot only provides temporary immunity so it will be necessary to have the shot given after each birth, miscarriage, or induced abortion.