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
Pearl index is used to calculate:March, September 2009 
Select and explain. 
A. Accidental pregnancies, B. Population, C. Feility rate, D. Aboions
A: Accidental pregnancies
Answer: A: Accidental pregnancies 
Explanation: Ans. A: Accidental PregnanciesMethods of contraception are compared by the Pearl index. A high Pearl index stands for a high chance of unintentionally getting pregnant; a low value for a low chance.The Pearl index will be determined by the number of unintentional pregnancies related to 100 women years. E.g. 100 women can contracept for 1 year each with the method that is going to be examined. If three pregnancies occur during this period in this group, the Pearl index will be 3.0.