Pearls index
Per 10 woman years
Per 100 woman years
Per 1000 woman years
Per 10,000 woman years
Pearl index is defined as the number of failures per 100 woman years of exposure (HWY) Failure rate per Hundred Women Years = Total accidental pregnancies X 1200/ Total months of exposure Reference : Park&;s textbook of preventive and social medicine, 23rd edition, Page no: 510
Demography and family planning