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
In Downs syndrome, the 2nd trimester quadruple test done at 14-20 weeks measure levels of all of the following, EXCEPT: 
Select and explain. 
A. Alpha fetoprotein, B. HCG, C. Inhibin A, D. Progesterone
D: Progesterone
Answer: D: Progesterone 
Explanation: The triple test (14 -20 weeks) measures the following three levels in the maternal serum: Alpha-fetoprotein (AFP) Human chorionic gonadotropin (hCG) Unconjugated estriol (UE3) Quadruple test done (14-20 weeks) measures levels of: Alpha-fetoprotein (AFP) Human chorionic gonadotropin (hCG) Unconjugated estriol (UE3) Inhibin A