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
Which of the following is not associated with increased risk of thromboembolism in pregnancy? 
Select and explain. 
A. Anaemia, B. Blood group O, C. Increases with rising parity, D. Antithrombin deficiency
B: Blood group O
Answer: B: Blood group O 
Explanation: 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