An O positive mother does not cause ABO incompatibility to her A negative fetus because the fetal immune system is not developed enough to create antibodies to the mother's antigens during pregnancy. An Rh- fetus has no antigens that could induce antibody creation in either an Rh- or Rh+ mother. Therefore, no problems are created between the mother's and fetus's blood groups during pregnancy.

1. Assignment
why mother blood group O positive does not
couse ABO incompatibility to her Anegative
fetus???
An Rh- fetus has no antigens to induce antibody creation in either an Rh- or
Rh+ mother. The fetal immune system is not yet developed enoughto
create antibodies to the mother’s antigens ,So no problem is created .
Dr. Isahak Ahmed Harir