This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetal Assessment, Subject name: Gynaecology & Obstetrics
[{'content': "Hasse's formula used in pregnancy to? \nSelect and explain. \nA. Estimate fetal age, B. Identify fetal blood group, C. Identify fetal sex, D. Identify fetal congenital malformations", 'role': 'user'}, {'content': "Answer: A \nExplanation: ANSWER: (A) Estimate fetal ageREF: Textbook of Forensic Medicine and Toxicology by Nagesh Kumar Rao - Page 321Hasse's formulaIf the crown heel length is known then the intrauterine age of fetus is calculated as:If CH length is up to 25 cm thenIU age = Square root of CH lengthIf the CH length is > 25 cm thenIU age = 1/5 of CH length", 'role': 'assistant'}]