This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Gynaecology & Obstetrics
[{'content': 'Extreme preterm is defined as \nSelect and explain. \nA. 34-36 weeks, B. 32-33 weeks, C. 28-31 weeks, D. < 28 weeks', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Preterm labor is defined as one where the labor stas before 37th completed week, counting from the first day of the last menstrual period Lower limit of gestation is - 20 weeks in developed countries 28 weeks in developing countries Ref: Dutta Obs 9e pg 294.', 'role': 'assistant'}]