women s health issues
Hemolytic Disease of the Fetus and Newborn
Introduction
Rh incompatibility occurs when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood. Rh incompatibility can result in destruction of the fetus’s red blood cells, sometimes causing anemia that can be severe. The fetus of a women with Rh-negative blood and a man with Rh-positive blood is checked periodically for evidence of anemia. If anemia is suspected, the fetus is given blood transfusions. To prevent problems in the fetus, doctors give injections of Rh antibodies to women with Rh-negative blood at about 28 weeks of pregnancy, 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: White people in North America and Europe: About 15% African American people: About 8% People of Chinese descent: About 0.3% People of Indian descent: About 5% Rh incompatibility does not cause problems in a first pregnancy. 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. Problems can occur if the fetus’s Rh-positive blood enters the bloodstream of a woman with Rh-negative blood. The woman’s immune system may identify the fetus’s red blood cells as foreign and produce Antibodies , called Rh antibodies, to destroy Rh-positive blood cells. 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. Once women are sensitized, problems are more likely with each subsequent pregnancy if the fetus’s blood is Rh-positive. In each pregnancy after sensitization, women produce Rh antibodies earlier and in larger amounts. If Rh antibodies cross the placenta to the fetus, they may destroy some of the fetus’s red blood cells. 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 Newborn (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 the Newborn ). In severe cases, the brain may be damaged (called Usually, Rh incompatibility causes no symptoms in pregnant women. 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. 