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The term "Rh Disease" is commonly used to refer to HDFN due to anti-D antibodies, and prior to the discovery of anti-Rh o (D) immune globulin, it was the most common type of HDFN. The disease ranges from mild to severe, and occurs in the second or subsequent pregnancies of Rh-D negative women when the biologic father is Rh-D positive.
The hemolytic condition occurs when there is an incompatibility between the blood types of the mother and fetus. There is also potential incompatibility if the mother is Rh negative, and the father is positive. When the mother conceives for the first time, with a positive child, she will become extremely sensitive.
The mother can make IgG anti-Rhc antibodies, which are able to pass through the placenta and enter the fetal circulation. If the fetus is Rhc positive alloimmune hemolysis can occur leading to HDN. This is similar as for Rh disease, which is usually caused when a RhD negative mother is sensitised by her first pregnancy with a RhD positive fetus.
Cell-free DNA can be used the determine the Rh antigen of the fetus when the mother is Rh negative. Blood is taken from the mother during the pregnancy, and using PCR, can detect the K, C, c, D, and E alleles of fetal DNA. This blood test is non-invasive to the fetus and is an easy way of checking antigen status and risk of HDN.
If the father is heterozygous, there is a 50% chance that the fetus will be RhD positive, as he will randomly pass on either the RhD positive allele or not. [9]: 130 . Not all Rh-negative patients are capable of being immunized to the RhD antigen, and mothers may only become immunized after many repeated pregnancies.
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, [1] [2] is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five main types of antibodies) produced by the mother pass through the placenta.
Other examples of insufficient immune tolerance in pregnancy are Rh disease and pre-eclampsia: Rh disease is caused by the mother producing antibodies (including IgG antibodies) against the Rhesus D antigen on their baby's red blood cells. It occurs if the mother is Rh negative and the baby is Rh positive, and a small amount of Rh positive ...
Individuals with a positive RhD status have RhD antigens expressed on the cell membrane of their red blood cells, whereas Rhesus D antigens are absent for individuals with a negative RhD status. Rhesus factor testing is usually performed on pregnant women to determine the RhD blood group of the mother and the fetus.