This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Types of Genetic Disorders, Subject name: Pediatrics
[{'content': 'Which of the following is a cause of decreased maternal serum a protein - \nSelect and explain. \nA. Neural tube defects, B. Fetal demise, C. Hepatitis, D. Aneuploidy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: | Maternal serum a - Fetoprotein Decreased Maternal Serum a fetoprotein Twins Neural tube defects Intestinal atresia Hepatitis Nephrosis Fetal demise Incorrect gestational age Trisomies Aneuploidy', 'role': 'assistant'}]