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
[{'content': 'Lactational amenorrhea is due to: \nSelect and explain. \nA. Prolactin induced inhibition of GnRH, B. Prolactin induced inhibition of FSH, C. Oxytocin induced inhibition of GnRH, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In breastfeeding females, prolactin levels are increased in response to suckling stimulus of breast feeding.\nBesides prolactin, FSH concentration are normal and LH concentration are low.\nDespite the presence of gonadotropin the ovary during lactation hyperprolactinemia dose\xa0not display follicular development and dose not secrete estrogen\nThese observations suggest that high concentrations of prolactin can work at both central levels(by inhibiting pulsatile secretion of GnrH) and peripheral level i.e. ovarian sites to produce lactational amenorrhea and anovulation\nThe principle pf GnrH suppression by prolactin is reinforced by the demonstration that treatment of amenorrheic, lactating women with pulsatile GrrH , fully restores pituitary secretion and normal ovarian cyclic activity', 'role': 'assistant'}]