<prompt> True about pearl index:Population studyFamily planningContraceptive methodsContraceptive failure  <response>: Ans. d Contraceptive failureRef: Parks PSM 21sted. 1472 Pearl index is used to measure the contraceptive efficacy contraceptive failure. It is defined as the number of failures per 100 women- years HWY of exposure.P Total accidental pregnancies---Total months of exposurex 1200 Another method used to measure contraceptive failure efficacy is life table analysis. Life table analysis: calculates failure rates for each month of use. 