Pearl's index indicates:

Ans. is c, i.e. Contraceptive failureRef: Dutta Obs 6th/ed, p532-532Pearl index indicates the effectiveness of a contraceptive or is an index of contraception failure.* It is expressed in terms of "failure rate per hundred women - years of exposure (HWY)".* Failure rate per HWY=No.ofpatientsobservedxmonthsofuseTotalaccidentalpregnanciesx1200(12x100) * In applying the above formula the following points must be kept in mind:a. The total accidental pregnancies shown in the numerator must include every known conception, whatever its outcome.b. The factor 1200 is the number of months in 100 years.c. The total months of exposure in the denominator is obtained by deducing from the period under review of 10 months for a full term pregnancy and 4 months for an abortion.