This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'The consequences of Rh incompatibility are not serious during first pregnancy because: \nSelect and explain. \nA. In first pregnancy only IgM antibody is formed, B. Antibody titer is very low during primary immune response, C. IgG generated is ineffective against fetal red cells, D. Massive hemolysis is compensated by increased eryth ropoiesis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: As discussed is the preceeding text – The initial antibodies which are produced are of IgM variety which cannot cross the placenta and by the time IgG antibodies develop, patient has already delivered. Thus first pregnancy is safe.\nAnother reason is\nIn sensitised women, anti-D antibodies are produced at such a low level that they are not detected during or after the index pregnancy. Instead, they are identified early in a subsequent pregnancy when rechallenged by another D-positive fetus.', 'role': 'assistant'}]