The Pearl Index for a contraceptive method is defined as the number of unintended pregnancies per:

• A 100 women using the method for 6 months
• B 1000 menstrual cycles of use
• C 100 women completing one full year of perfect use
• D 100 woman-years of use ✓

Explanation

The Pearl Index = (Number of unintended pregnancies / Total months of exposure) × 1200, expressed as failures per 100 woman-years of use. It allows comparison across studies with different follow-up durations. A lower Pearl Index indicates greater effectiveness. It has limitations — the denominator of woman-years is skewed toward shorter use (pregnancies remove women from the denominator) and does not account for failure rate variation over time (Life-table analysis is superior). Perfect use vs typical use Pearl Index differ substantially for user-dependent methods.

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.