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
All are true regarding renal changes in normal pregnancy except 
Select and explain. 
A. Serum creatinine decreases., B. GFR and Renal plasma flow increase by 50%., C. Increase in serum bicarbonate levels., D. Increased placental metabolism of AVP may cause transient diabetes insipidus during pregnancy.
C: Increase in serum bicarbonate levels.
Answer: C: Increase in serum bicarbonate levels. 
Explanation: Serum bicarbonate levels decreased by 4 → 5m Eq / L due to decreased renal bicarbonate threshold.