We'd like to understand how you use our websites in order to improve them. Register your interest. The double ABO- and Rh-incompatibility between mother and child generally affords complete protection against anti-Rh immunization; on very rare occasions the protective mechanism fails; sometimes the ABO-antagonism results in the delayed appearance of low-titered anti-Rh antibodies. The significance of this phenomenon cannot be understood unless all the antigenic stimuli are known in detail. The available data are as yet insufficient and their analysis should be limited to the two-children families.
|Published (Last):||5 October 2006|
|PDF File Size:||1.20 Mb|
|ePub File Size:||3.6 Mb|
|Price:||Free* [*Free Regsitration Required]|
Rh incompatibility occurs when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood. To prevent problems in the fetus, doctors give injections of Rh antibodies to women with Rh-negative blood at about 28 weeks, after any episode of significant bleeding, after delivery, and after certain procedures.
Pregnancy complications, such as Rh incompatibility, are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. However, most pregnancy complications can be effectively treated. The fetus of a woman with Rh-negative blood may have Rh-positive blood if the father has Rh-positive blood.
The percentage of people who have Rh-negative blood is small and varies by ethnicity:. The Rh factor is a molecule on the surface of red blood cells in some people. Blood is Rh-positive if red blood cells have the Rh factor and Rh-negative if they do not. The production of these antibodies is called Rh sensitization. Antibodies are proteins that are produced by immune cells that help defend the body against foreign substances.
In women with Rh-negative blood, sensitization can occur at any time during pregnancy. However, the most likely time is at delivery.
In the pregnancy when sensitization first occurs, the fetus or newborn is not likely to be affected. In each pregnancy after sensitization, women produce Rh antibodies earlier and in larger amounts. If red blood cells are destroyed faster than the fetus can produce new ones, the fetus can develop anemia. Such destruction is called hemolytic disease of the fetus erythroblastosis fetalis or of the newborn erythroblastosis neonatorum.
When red blood cells are destroyed, a yellow pigment called bilirubin is produced. When many red blood cells are destroyed, bilirubin can accumulate within the skin and other tissues. As a result, the newborn's skin and whites of the eyes may appear yellow called jaundice. In severe cases, the brain may be damaged called kernicterus , and severe anemia can result in the fetus's death. Miscarriage can occur.
Occasionally, other molecules on the woman's red blood cells are incompatible with those of the fetus. Such incompatibility can cause problems similar to those of Rh incompatibility. At the first visit to a doctor during a pregnancy, women are screened to determine whether they have Rh-positive or Rh-negative blood.
If they have Rh-negative blood, their blood is checked for Rh antibodies. If the father is unavailable for testing or if he was tested and he has Rh-positive blood, a blood test called cell-free fetal nucleic acid DNA testing can be done to determine whether the fetus has Rh-positive blood.
For this test, doctors test small fragments of the fetus's DNA, which are present in the pregnant woman's blood in tiny amounts usually after 10 to 11 weeks. After the risk of Rh sensitization is determined, doctors can measure the level of Rh antibodies in the mother's blood. If the level reaches a certain point, the risk of anemia in the fetus is increased. If it is abnormal, the fetus may have anemia. As a precaution, women who have Rh-negative blood are given an injection of Rh antibodies at each of the following times:.
Within 72 hours after delivery of a baby who has Rh-positive blood, even after a miscarriage or an abortion. The antibodies given are called Rh0 D immune globulin. Thus, the woman's immune system does not make antibodies to the Rh factor. If the fetus has Rh-negative blood or if results of tests continue to indicate that the fetus does not have anemia, the pregnancy can continue to term without any treatment.
If anemia is diagnosed in the fetus, the fetus can be given a blood transfusion before birth by a specialist at a center that specializes in high-risk pregnancies. Most often, the transfusion is given through a needle inserted into a vein in the umbilical cord.
Usually, additional transfusions are given until 32 to 35 weeks of pregnancy, when doctors may recommend that the baby be delivered. Exact timing of the transfusions depends on how severe the anemia is and the fetus's age.
Before the first transfusion, women are often given corticosteroids if the pregnancy has lasted 23 or 24 weeks or longer. Corticosteroids help the fetus's lungs mature and help prevent the common complications that can affect a preterm newborn.
The baby may need additional transfusions after birth. Sometimes no transfusions are needed until after birth. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.
The Merck Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here.
Common Health Topics. Commonly searched drugs. Ranitidine Withdrawn from US Market. Brought to you by. Complications of Pregnancy. Test your knowledge. Prenatal diagnostic testing involves testing the fetus before birth prenatally to determine the presence of certain abnormalities.
Abnormalities can include hereditary or spontaneous genetic disorders. Which of the following tests involves NO risk to the fetus? More Content. Click here for the Professional Version. Rh incompatibility does not cause problems in a first pregnancy. Did You Know Blood tests. If the woman's blood contains Rh antibodies, Doppler ultrasonography.
Doctors usually assess the risk that women will become sensitized to Rh factor as follows:. If the father is known and is available for testing, his blood type is determined. At 28 weeks of pregnancy.
For anemia in the fetus, blood transfusions. Generic Name Select Brand Names immune globulin. Was This Page Helpful? Yes No. Rh Incompatibility. Hemolytic Disease of the Newborn. Jaundice in the Newborn. Chorionic Villus Sampling. Contents of the Female Pelvis.
La protection contre l'immunisation anti-Rh conférée par l'incompatibilité ABO
Monfort, T. Peyrard, T. Peyrard, C. Journal page Archives Contents list. Benahadi, R. Alami, S. Boulahdid, B.
Journal page Archives Contents list. Article Article Outline. Access to the text HTML. Access to the PDF text. Recommend this article. Save as favorites. Access to the full text of this article requires a subscription.