What is Erythroblastosis Fetalis

But if the mother, who is Rh-sensitized by the first pregnancy, has subsequent pregnancies, she will have produced sufficient antibodies that can diffuse into the blood of an Rh-positive fetus and react with its erythrocytes. This agglutination of the blood of the fetus with the antibodies produced in its mother is a disease known as erythroblastosis fetalis.

Erythroblastosis fetalis occurs when

Besides the A and B agglutinogens, there is another type of blood antigen, designated the Rh factor. There are eight different types of Rh antigens that may be present on human erythrocytes. Humans are classified into two groups with respect to the Rh antigen: Rh-positive individuals have an Rh antigen, while Rh-negative individuals have such a weakly antigenic factor that it can be disregarded. The A―B―O blood type system is an example of a rare case in which the body normally synthesizes antibodies in large amounts against an antigen to which it has not yet been exposed.

Causes of Erythroblastosis fetalis

The Rh system follows the rule rather than the exception. An individual's plasma will not con­tain antibodies against the Rh antigen unless it has been sensitized to the antigen by previous exposure. Thus, while Rh-positive individuals have the Rh antigen, Rh-negative individuals have neither an effective antigen nor an antibody against the antigen. If Rh-positive blood is given to Rh-negative individuals, the Rh-negative individual will gradually synthesize antibodies against the Rh antigen introduced. Agglutination of the cells occurs, plugging up the small blood vessels, inactivating the erythrocytes as oxygen carriers, and eventually leading to the death of the recipient.

Erythroblastosis in the first babies

In our particular problem, the couple's first child might inherit the Rh-negative characteristic. There is thus no particular problem since the mother is also Rh-negative. But if the fetus is Rh-positive, trouble may occur. If some blood from the Rh-positive fetus enters the maternal circulation, its antigens stimulate the mother's plasma cells to synthesize Rh antibodies. Normally, the mother cannot produce antibodies rapidly enough and in large enough amounts to affect the first child before birth.

Erythroblastosis fetalis effects

But if the mother, who is Rh-sensitized by the first pregnancy, has subsequent pregnancies, she will have produced sufficient antibodies that can diffuse into the blood of an Rh-positive fetus and react with its erythrocytes. This agglutination of the blood of the fetus with the antibodies produced in its mother is a disease known as erythroblastosis fetalis.

Erythroblastosis fetalis explanation:

Only about 3% of the second or later Rh-positive fetuses born to Rh-negative mothers show signs of erythroblastosis fetalis. The blood of the mother may not diffuse into the fetal circulation, thus preventing agglutination. In addition, only one of the types of Rh antigens is responsible for erythroblastosis; other forms will not cause any trouble.

Erythroblastosis autoimmune disease

Also, the longer the time interval between pregnancies, the less intense is the anti-Rh immune response in the mother. One method of preventing erythroblastosis is to in­ject Rh antibodies into an Rh-negative mother immediately after the birth of her first Rh-positive infant. The antibodies kill any fetal red blood cells that have entered her circulation and thus prevent the stimulation of maternal antibody production. The injected antibodies eventually are destroyed arid the mother is now unsensi­tized and able to bear a second Rh-positive infant.