The 'Pearl Index' of a contraceptive method is calculated as the number of unintended pregnancies per:

• A 100 women per month of use
• B 1000 woman-cycles of use
• C 100 women completing the method for 1 year
• D 100 woman-years of exposure ✓

Explanation

Pearl Index = (Number of unintended pregnancies / Total woman-months of exposure) × 1200 = number of pregnancies per 100 woman-years. It is the standard measure of contraceptive effectiveness; a lower Pearl Index indicates greater efficacy. Cu-IUCD 380A has a Pearl Index of 0.6–0.8; combined OCP ~0.3 with perfect use; male condom ~2 with perfect use and ~15 with typical use; rhythm method ~3–20. The denominator is woman-years (or woman-months × 12 factor correction).

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.