A woman had three pregnancies. Firstborn healthy, second severely jaundiced requiring exchange transfusion, third stillborn. Most likely cause?

• A. ABO incompatibility
• B. Maternal infection
• C. Rh incompatibility
• D. Fetal aneuploidy

Answer: (C)

Rh incompatibility explains this pattern. If the mother is Rh-negative and the fetus is Rh-positive, fetal red cells can enter the mother’s circulation during delivery, triggering the production of anti-D IgG antibodies. In later pregnancies, these antibodies cross the placenta and destroy fetal red cells, causing severe hemolysis, anemia, and hyperbilirubinemia in the fetus/newborn. That’s why the second pregnancy may present with severe jaundice requiring exchange transfusion, and a subsequent pregnancy with an Rh-positive fetus can result in fetal demise or stillbirth due to profound anemia. ABO incompatibility tends to cause milder jaundice and often affects the first pregnancy, while maternal infection or fetal aneuploidy don’t produce this exact sequence of a benign first pregnancy followed by a severely affected second and a stillborn third.