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What is Contraceptive efficacy expressed as and explain in detail?
Contraceptive efficacy is assessed by measuring the number of unplanned pregnancies that occur during a specified period of exposure and use of contraceptive methods.Contraceptive efficacy is measured using Pearl index and life table analysis. Pearl index is number of failure per 100 woman-years of exposure (HWY) HWY=total accidental pregnancies/total months of exposure.*1200 Life table analysis measure failure rate per month of exposure. Park&;s textbook of preventive and social medicine.K Park. Edition 23.Pg no: 510