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
Related to calcium metabolism, which of the following does not occur during pregnancy 
Select and explain. 
A. Total serum calcium levels fall., B. 80% of fetal calcium deposition occurs in third trimester., C. Fetal skeleton excretes approximately 30g of calcium by term., D. Serum ionized calcium levels fall.
D: Serum ionized calcium levels fall.
Answer: D: Serum ionized calcium levels fall. 
Explanation: Serum ionized calcium levels remain unchanged in pregnancy.