The Pearl Index for a contraceptive method is defined as the number of contraceptive failures per:
- A 1,000 woman-months of exposure
- B 100 woman-years of exposure ✓
- C 100 completed pregnancies
- D 1,000 women using the method for one year
Correct answer: B. 100 woman-years of exposure
Explanation
Pearl Index = (Number of accidental pregnancies / Total months of exposure) × 1,200, expressed as failures per 100 woman-years. It is the standard measure of contraceptive effectiveness. Perfect-use (method failure) and typical-use (user failure) Pearl Indices differ substantially. For COCs: perfect use Pearl Index ~0.3; typical use ~9. For male condoms: perfect use ~2; typical use ~18. For Cu-IUD (380A): ~0.6-0.8. A lower Pearl Index indicates greater contraceptive efficacy. The formula ×1,200 converts months to years (1,200 = 100 × 12).
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.