Contraceptive efficacy measured by -

(A) (Pearl index) (471 - Park 22nd)Pearl index and life table analysis** are used to measure contraceptive efficacy(A) PEARL INDEX is defined as the number of failures per 100 woman - years of exposure (HWY)Failure rate per HWY =Total accidental pregnancies------------------Total months of exposurex 1200* The factor 1200 is the number of months in 100 years*** Total month of exposure in the denominator is obtained by deducting from period under review of 10 months for a full term pregnancy and 4 months for an abortion.* Pearl index limitation is over come by using the method life-table analysis***(B Life-Table Analysis:* Calculative failure rate for each months of use*** A cumulative failure rate can then compare methods for any specific length of exposure.* Women who leave a study for any reason other than unintended pregnancy are removed from the analysis contributing their exposure until the time of the exit.