What condition most often arises in Rh-negative mothers with a second Rh-positive fetus?

The condition that most often arises in Rh-negative mothers with a second Rh-positive fetus is erythroblastosis fetalis. This condition develops when an Rh-negative mother is exposed to Rh-positive blood from her fetus, typically during the first delivery or due to some bleeding during pregnancy. The mother’s immune system may produce antibodies against the Rh factor. If the mother becomes pregnant with another Rh-positive fetus, those antibodies can cross the placenta and attack the red blood cells of the fetus, leading to anemia and other complications associated with erythroblastosis fetalis.

This condition is serious and can result in significant health issues for the fetus, including jaundice, heart failure, and even death if not treated effectively. Prevention of this condition typically involves administering Rh immunoglobulin to the mother during and after the first pregnancy to prevent the formation of antibodies against Rh-positive blood in future pregnancies.

While hemolytic disease of the newborn is closely related to this condition and may be a consequence of it, erythroblastosis fetalis specifically describes the condition characterized by the fetal body's reaction to maternal antibodies. Coombs syndrome generally refers to a form of hemolytic disease associated with incompatible blood types, but it is not a condition that specifically highlights the mechanism involving Rh incompatibility