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': 'Fibronectin in fetus indicates: \nSelect and explain. \nA. Post dated pregnancy, B. Preterm labor, C. Pre-eclampsia, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Preterm labor', 'role': 'assistant'}]