This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in Obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': '|ed maternal serum a-FP is seen in: \nSelect and explain. \nA. Multiple pregnancy, B. Trisomy 21, C. Open neural tube defect, D. IUD', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is b, i.e. Trisomy 21Ref. Williams Obs. 25/e, p 287; Fernando Arias 2/e, p 38Low levels of MSAFP (< 0.25 MOM) are seen in:Devils: Diabetes mellitusG: Gestational trophoblastic diseaseO: Overestimated gestational age Maternal ObesityA: AbortionT: TrisomyNote: The list given in the Williams Obs. 25/e, p 291 -- Includes fetal death both in causes of increased and decreased AFP. But Fernando Arias 2/e, p 38 specifically includes -- IUD in the causes of increased AFP and Blighted ovum/Abortion in the causes of decreased AFP', 'role': 'assistant'}]