This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endometriosis, Adenomyosis, Subject name: Gynaecology & Obstetrics
Mechanism of action of progesterones in the medical management of endometriosis is? 
Select and explain. 
A. Deccidualisation and endometrial atrophy, B. Prevention of retrograde menstruation, C. Thickening of cervical mucous, D. Prevention of ovulation
A: Deccidualisation and endometrial atrophy
Answer: A: Deccidualisation and endometrial atrophy 
Explanation: Progesterones act by exeing an anti estrogenic effect and their continuous administration causes decidualisation and endometrial atrophy. The treatment over a period of 6 - 9 months produces a state of pseudopregnancy which ultimately causes regression of disease. It has no effect on ovulation Progestins used commonly are: Norethisterone Dydrogesterone Medroxyrogesterone acetate Mirena IUCD Dienogest