The failure rate per HWY of Pearl index is given by
The Pearl index is defined as the number of failures per 100 women-years of exposure . This rate is given by the formula:Failure rate per HWY: x 1200The factor 1200 is the number of months in 100yearsRef: PArk; 23rd ed; Pg 510
x 1200
x 2400
x 1200
x 2400
Demography and family planning