It is a condition that develops when Rh-negative women is pregnant with Rh-positive baby .
It causes phagocytosis of the fetus's RBC's (Baby inherits Rh positive antigen from father ).
As mother is Rh-negative , exposure to fetus's antigen causes development of anti-Rh agglutinins .
These agglutinins(mostly IgG antibody ) diffuse through the placenta and enters fetus blood cells and leads to phagocytosis of the RBCs ,which leads to release of hemoglobin into blood !Then fetus's macrophages converts the hemoglobin into bilirubin ,which causes baby skin to become yellow(jaundiced).Although the severe form of anemia is responsible for many deaths of infants ,many children who barely survive the anemia exhibit permanent mental impairment , because of precipitation of bilirubin in the neuronal cells ,causing destruction of many cells , condition known as Kernicterus
It usually doesn't affect the first child ,since sensitization occurs during parturition.However ,if Rh-negative mother was sensitized earlier with Rh antigen then first child can get affected .
1)One treatment of HDNF is to replace the neonate's blood with Rh-negative blood .About 400ml of Rh negative blood is infused over a period of 1.5 or more hours ,while neonate's own blood is removed,the process may be repeated several times during the first week of life ,to prevent Kernicterus .
Anti-D antibody is administered to the expectant mother ,starting at 28-30 weeks of gestation.The anti -D antibody is also administered to Rh-negative women who deliver Rh -positive babies to prevent sensitization of the mothers to the D antigen .This greatly reduces the risk of developing large amounts of D antibodies during second pregnancy !