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': 'All are risk factors for preterm delivery except : \nSelect and explain. \nA. Absence of fetal fibronectin at < 37 weeks, B. Previous history of preterm baby, C. Asymptomatic cervical dilatation, D. Chylamydial infection of genital tract', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Absence of fetal fibronectin at < 37 weeks', 'role': 'assistant'}]