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': 'Post paum hemorrhage in a spontaneous delivery is commonly due to: September 2005, March 2013 \nSelect and explain. \nA. Traumatic, B. Uterine atony, C. Blood coagulopathy, D. Mixed causes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: Uterine Atony Atonic uterus is the most common cause of PPH (80%) followed by traumatic (20%)', 'role': 'assistant'}]