This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Labour - normal, abnormal, malposition, malpresentation and their management, Subject name: Gynaecology & Obstetrics
All of the following drugs are effective for cervical ripening during pregnancy except: 
Select and explain. 
A. Prostaglandin E2, B. Oxytocin, C. Progesterone, D. Misoprostol
C: Progesterone
Answer: C: Progesterone 
Explanation: Progesterone is pregnancy protective agent and is given for maintenance of pregnancy and is even used as a tocolytic in preterm labour. Protaglandin E1 is misoprostol, E2 is Dinoprostone along with oxytocin are regularly used for cervical ripening for inducing labor or even for inducing aboions.