The Pearl Index for a contraceptive method is calculated as:
- A (Number of pregnancies / Number of women studied) × 100
- B (Number of pregnancies × 1200) / (Total months of exposure) ✓
- C (Number of failures / Woman-years of observation) × 100
- D Probability of pregnancy in one menstrual cycle
Correct answer: B. (Number of pregnancies × 1200) / (Total months of exposure)
Explanation
Pearl Index = (Number of accidental pregnancies × 1200) / Total months of exposure. This standardizes failure rates per 100 woman-years. For example, if 3 pregnancies occur in 200 women over 6 months (1200 months total), Pearl Index = 3 × 1200/1200 = 3 per 100 woman-years. A lower Pearl Index indicates greater contraceptive efficacy. The ideal Pearl Index is 0 (perfect contraception).
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.