The 'Pearl Index' is used to measure contraceptive efficacy. A method with a Pearl Index of 2.0 means:

• A 2% of users will become pregnant in their lifetime with this method
• B 2 pregnancies occur per 100 woman-years of use ✓
• C The method prevents pregnancy in 98% of cycles
• D There is a 2-day window of contraceptive failure per cycle

Explanation

Pearl Index = (Number of accidental pregnancies × 1200) / (Number of woman-months of exposure). It expresses the number of pregnancies per 100 woman-years (equivalent to 1200 woman-months). A Pearl Index of 2.0 means 2 unintended pregnancies per 100 women using the method for one full year (or equivalently, per 1200 woman-months). This is distinct from percentage of cycles (option C) and is an exposure-time-based measure, not a lifetime or per-cycle measure. The Pearl Index is simple but has limitations — it assumes constant failure rate throughout observation, does not account for user dropout, and can be influenced by study duration.

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.