This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Physiological Changes of Pregnancy, Subject name: Gynaecology & Obstetrics
All of the following may be observed in a normal pregnancy EXCEPT: 
Select and explain. 
A. Fall in serum iron concentration, B. Increase in serum iron binding capacity, C. Increase in blood viscosity, D. Increase in blood oxygen carrying capacity
C: Increase in blood viscosity
Answer: C: Increase in blood viscosity 
Explanation: Blood thins out in pregnancy due to the hemodilution of pregnancy. The increase in Blood volume (30-45%) is relatively greater than that of red cell mass (20-30%) resulting in hemodilution and a decrease in haemoglobin concentration. Fibrinogen as well as factors VII , IX, X and XII increase markedly. These changes tend to prevent excessive bleeding at delivery. Pregnancy is a hyper-coagulable state thus, but this is not synonymous with "Increased viscosity" .