This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pathology of Conception, Subject name: Gynaecology & Obstetrics
[{'content': 'In ovarian cycle increased levels of LH are due to: \nSelect and explain. \nA. Increased progesterone, B. Increased estrogen, C. Increased FSH, D. Increased androgens', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. Increased estrogen In ovarian cycle increased levels of LH are due to Increased estrogen.Estrogen has a positive feedback on LH near ovulation and therefore levels of LH are suddenly increased resulting in LH surge."With dramatic increase in estradiol, however there is a change in the LH feedback. There is initial suppression of LH with low levels of estradiols. It switches to positive feedback when estradiol levels reach 200 pg/ml. These high estrogen level also increases the production of more bioactive form of FSH and LH. This causes the dramatic bioovulatory LH surge causing 10 fold increase in LH. Sheila Balakrishnan l/e p34', 'role': 'assistant'}]