Pearl Index (Contraceptive Efficacy)

Health

Calculate Pearl Index for contraceptive efficacy. Formula: (Unintended Pregnancies × 1200) / (Number of Cycles Exposed). Lower is better; typical <1 for IUD/sterilization.

Formula

Pearl Index = (Pregnancies × 1200) / Woman-Months

1 pregnancy, 1200 woman-months

Inputs
  • Unintended Pregnancies: 1
  • Total Woman-Months Exposed: 1200

Pearl = 1.0 (1 failure per 100 woman-years)

Frequently asked questions

Interpretation?
<1 excellent, 1-10 good, >10 acceptable