Question

Out of 100 women offered oral contraceptive pills, 10 women became pregnant when followed for 24 months. What is the Pearl Index?

• A. 10
• B. 5
• C. 4
• D. 2

Hint:

Pearl Index = pregnancies x 1200 / (women x months).

Answer 1

The Correct Option is B

Step 1: The Pearl Index expresses contraceptive failures per 100 woman-years of exposure. Its formula is \[\text{Pearl Index} = \frac{\text{number of pregnancies} \times 12}{\text{number of women} \times \text{number of months}} \times 100.\] Step 2: Substitute the given values - 10 pregnancies, 100 women, 24 months of follow-up: \[\text{Pearl Index} = \frac{10 \times 12}{100 \times 24} \times 100.\] Step 3: Compute the numerator and denominator: \[= \frac{120}{2400} \times 100 = 0.05 \times 100 = 5.\] Step 4: A lower Pearl Index means a more effective method. The value here is 5, so option B is correct.