This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non-Hormonal - Barrier Methods, Subject name: Gynaecology & Obstetrics
[{'content': 'Highest failure rate is seen in: \nSelect and explain. \nA. OCP, B. Condom, C. Cu-T, D. Depot injection', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (Condom) Ref: Shaw, 13th ed, p. 217Measurement of contraceptive efficacyPearl index: -Pregnancy rate per 100 women yearsPearl index =Total accidental pregnancy x 1200Total months of exposure to unintended pregnancyLife table techniquePregnancy rate is expressed as 100 women per year.Failure rates CondomNatural FP methodSpermicidesWithdrawalOther vaginal barriers1221211821 IUCD - Medicated1Inert3Progesterone only pill3Combined OCP1 -8 (0.1 if correctly used)Injectable contraceptive0.1 -0.4Female sterilization0.4Vasectomy0.2Implant0.4', 'role': 'assistant'}]