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': 'Post term labour is seen in: \nSelect and explain. \nA. Hydramnios, B. PID, C. Anencephaly, D. Multiple pregnancy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Causes of Post-term pregnancy:\n\nWrong dates: due to inaccurate LMP (most common).\nBiologic variability (Hereditary) may be seen in the family.\nMaternal factors: Primipara/elderly multipara/H/o previous prolonged pregnancy, sedentary habit.\nFetal factors: Congenital anomalies: Anencephaly – (Abnormal fetal HPA axis), adrenal hypoplasia (Diminished fetal cortisol response).\nPlacental factors: Sulphatase deficiency (Low oestrogen).', 'role': 'assistant'}]