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': 'Hasse’s formula used in pregnancy to? \nSelect and explain. \nA. Identify sex age, B. Identify fetal blood group, C. Estimate fetal age, D. Identify fetal congenital malformations', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hasse’s formula If the crown-heel length is known then the intrauterine age of the fetus is calculated as:\nIf CH length is up to 25 cm then IU age = Square root of CH length If the CH length is > 25 cm then IU age = 1/5 of CH length', 'role': 'assistant'}]