Question

Erythroblastosis fetalis is caused when mother is
A. Rh $+ ve$
B. With blood group AB positive
C. Rh $- ve$
D. None of the above

Answer 1

Erythroblastosis fetalis is hemolytic anemia in the fetus or neonate that is caused by transplacental transmission of maternal antibodies to the fetal red blood cells. The disorder usually occurs due to the incompatibility between the maternal and the fetal blood groups. There are two main causes of erythroblastosis fetalis which are Rh incompatibility and also ABO incompatibility.

Complete answer:
When the female is pregnant, blood from the baby can cross into the bloodstream, especially during the process of delivery.
When the mother is Rh positive which means the mother has Rh antigens, erythroblastosis fetalis does not occur. Antigens are basically the substances which can trigger an immune response in your body.
When the mother’s blood group is AB positive, erythroblastosis fetalis does not occur because there is presence of Rh antigens in the mother’s body.
If the mother is Rh negative and the baby is Rh positive which means there is presence of Rh antigens, the mother's body will react to the baby's blood as a foreign substance because there is an incompatibility between the maternal and the fetal blood groups. It will create antibodies or proteins against the baby's blood. These antibodies usually don't cause problems during a first pregnancy but can cause complications in later pregnancies.

So the correct answer is option C.

Note:
To diagnose erythroblastosis fetalis, a doctor will first order a routine blood test during the first prenatal visit. This test will also help them determine whether the mother has anti Rh antibodies in blood from a previous pregnancy. If the mother has Rh negative blood, then the father’s blood will be tested. If the father’s blood type is Rh negative, then no further testing is required.