What is the Rh Factor
The Rh factor is the type of protein found on the red blood cells. Most individuals have the Rh factor and are consider Rh-positive. Others do not have the Rh factor and are considered Rh-negative. A simple blood test during pregnancy will determine if you are Rh-positive or Rh-negative.
The Rh factor does not affect a person’s overall health. But can cause problems during pregnancy. In most cases, these problems can be prevented by taking special medications.
When does the Rh Factor cause problems?
The Rh factor causes problems when a Rh-negative person’s blood comes in contact with Rh-positive blood. If this happens, the person with Rh-negative blood may become sensitized. This means they produce antibodies that fight the Rh factor as if it were a harmful substance.
During pregnancy, the woman and fetus do not share blood systems. However, a small amount of blood from the fetus can cross the placenta into the women’s systems. When this happens a small number of women with Rh-negative blood who carry a Rh-positive fetus will react as if they are were allergic to the fetus. The mother becomes sensitized and makes antibodies that break down the fetal red blood cells. This causes anemia which can lead to a serious illness, brain damage or even death of the fetus or newborn.
These antibodies once formed do not go away. In a first pregnancy with a Rh-positive fetus the baby is often born before the antibodies develop, so there may be no serious problems. In a second pregnancy with a Rh-positive fetus, these antibodies are more likely to cause anemia in the fetus. In most cases the condition becomes worse in later pregnancies.
A woman can be sensitized any time Rh-positive blood mixes with her blood. This can occur if an Rh-negative woman has once had:
- A miscarriage
- An induced abortion
- An ectopic pregnancy
- A blood transfusion
- Amniocentesis
- Chorionic villus sampling (CVS)
- Bleeding during pregnancy
How can problems be prevented?
A simple blood test during pregnancy will identify Rh factor. An additional blood test called an antibody screen, can show if a Rh-negative woman has developed antibodies to Rh-positive blood.
Anemia can be prevented in the fetus if the woman has not yet made antibodies against the Rh factor. Rh immunoglobulin (RhIg) is a blood product that can prevent a Rh-negative mother from being sensitized, by preventing her body from responding to Rh-positive blood cells of the fetus.
If a Rh-negative woman is given RhIg it will likely be injected into a muscle of the arm or buttocks. Side effects include soreness at the injection site or a slight fever. Usually both will go away on their own.
When is RhIg used?
During pregnancy and After Delivery
If a woman with Rh-negative blood has not been sensitized her doctor may suggest that she receive RhIg around the 28th week of pregnancy to prevent sensitization. This will prevent problems in a small number of women who can become sensitized during the last three months.
After birth if the child has Rh-positive blood the mother will be given another dose of RhIg. This prevents the women from making antibodies to Rh-positive blood cells she may have received during delivery. If the baby is Rh-negative no treatment is needed.
For future pregnancies and deliveries the mother will require a repeat dose of RhIg for each Rh-positive child.
Other reasons RhIg may be given
Treatment should be given to Rh-negative women any time the blood meets the fetus. This includes during miscarriage, ectopic pregnancy, induced abortion, amniocentesis or chorionic villus sampling.
What happens if Antibodies develop?
If a woman has already developed antibodies, RhIg treatment will not help. A mother who is Rh-sensitized will be checked ruing her pregnancy to see if the fetus is at risk.
In some severe cases, a baby with anemia may be give blood transfusions while in the uterus or delivered early. In less severe cases, the baby may need a transfusion after delivery to replace the blood cells.
Finally. . .
All women in the early stage of pregnancy should have a blood test to protect against Rh sensitization.
