<prompt> 100 women were surveyed for oral contraceptive pill usage for 24 months, out of which 10 became pregnant. Calculate the pearl index?2.551020  <response>: Ref. Foundations of Community medicine. Page.117 Pearl IndexIt measures the contraceptive efficacy.It is defined as the number of failures per 100 woman years of exposureThis rate is given by the formula Total accidental pregnancies 1200 Number of women Number of month Pearl Index 10 × 12 × 100 100 × 24 5 