Final answer:
If the Rh-negative mother did not receive RhoGAM and is carrying a second Rh-positive child, there is a risk of HDN or erythroblastosis fetalis, which can be fatal for the fetus due to hemolytic anemia.
Step-by-step explanation:
There is cause for concern if a young pregnant mother is Rh-, her husband is Rh+, and this is their second child because of the risk of hemolytic disease of the newborn (HDN) or erythroblastosis fetalis. In the case of a second Rh+ child, if the mother did not receive prophylactic treatment with RhoGAM during her first pregnancy or her current pregnancy, the anti-Rh antibodies she developed after the first pregnancy could cross the placenta and result in the destruction of the Rh+ red blood cells of the fetus. This immune reaction may lead to HDN, a condition that can cause severe hemolytic anemia in the fetus and may result in death before birth if left untreated.