Rh sensitizarin of a preganant woman by Foetal Rh antigen -How & wen?

IgM antibodies in Rh antigen are harmless but IgG ab are harmful to foetus. The significance of being Rh Negative or Rh Positive:- Here some quick recapitulation:- The Rh factor is a protein that can be observed on the surface of red blood cells .  The rhesus protein is named for the rhesus monkey, which also carries the same gene, and is a protein that lives on the surface of the red blood cells.   Being Rh-negative itself does not cause miscarriage or pregnancy losses. One is only at risk if  she been sensitized by Rh cells like previous Rh +ve blood tr or Rh antigens coming along with Rh +ve foetal blood cells as FMH  in preg period (FMH-fetomaternal hemorrhage). The risk is very small if one have the recommended RhoGAM shots during pregnancy, or after an ectopic pregnancy, pregnancy loss, or induced abortion, CVS, amniocentesis or APH .

How does a person get the Rh factor? The Rh factor is inherited, meaning it is passed from parent to child through genes. The fetus can inherit the Rh factor from the father or from the  mother.

Can the Rh factor cause problems during pregnancy?

Yes. During pregnancy, problems can occur if one is  Rh negative and your fetus is Rh positive. When a woman is Rh negative and her fetus is Rh positive, it is called Rh incompatibility. What is Rh sensitization during pregnancy?

If one is  Rh-negative, her red blood cells do not have a marker called Rh factor on them. Rh-positive blood does have this marker. If her  blood mixes with Rh-positive fetal / transfused blood, then the recipients/ mothers  immune system will react to the Rh factor supplied by FMH à  by making antibodies to destroy the Rh antigen . Development of this  immune system response is called Rh sensitization.

What causes Rh sensitization during pregnancy? During birth or throughout the pregnancy, the mother may be exposed to the infant's blood, and this causes the immune system to respond to the red blood cells as foreign protein by maternal immune system and mount a response by creating antibodies. During the first pregnancy, the initial exposure to fetal RBCs results in the formation of IgM antibodies, and these do not cross the placental barrier, which is why no effects are seen in first pregnancies for Rh-D mediated disease.

However, in subsequent pregnancies, the immune system mounts a memory response when re-exposed, and these antibodies (IgG) do cross the placenta into fetal circulation. These antibodies are directed against a protein found on the surface of the fetal red blood cells (RBCs). The antibody coated fetal red blood cells are destroyed. The resulting anemia has multiple sequelae