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': 'Which of the following is not associated with increased risk of thromboembolism in pregnancy? \nSelect and explain. \nA. Anaemia, B. Blood group O, C. Increases with rising parity, D. Antithrombin deficiency', 'role': 'user'}, {'content': "Answer: B \nExplanation: Age > 35 years, smoking and blood groups other than 'O' are associated with | risk of thromboembolism in pregnancy. Ref: Karla Philip, 3rd Edition, Page 312", 'role': 'assistant'}]