This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and Reproduction, Subject name: Physiology
[{'content': 'Most common cause of secondary amenorrhea is \nSelect and explain. \nA. Hypogonadism, B. Hypopituitarism, C. Pregnancy, D. Ovarian tumor', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C. i.e. (Pregnancy) (447- Ganong 22nd) (422 - Ganong 23rd)* If menstrual bleeding has never occurred the condition is called primary amenorrhea* Cessation of cycle in a woment with previously normal periods is called secondary amenorrhea. The commonest cause of secondary amenorrhea is pregnancy*** Effect of pregnancy on respiration is - Increased tidal volume*** Sec-amenorrhoea is - Absence of menstruation for > 6 months*** Hypothalamic amonorrhoea is seen in - Kallaman *s syndrome**', 'role': 'assistant'}]