Analyzing Contraceptive Failure Rates

The question asks to identify correct statements regarding the annual failure rates of specific contraceptive methods, measured per 100 woman-years (HWY).

Statement 1: Depot medroxyprogesterone acetate (DMPA)

DMPA is an injectable contraceptive. Its typical failure rate is very low, around 0.2-0.3 pregnancies per 100 woman-years ($\approx 0.2-0.3 \text{ per HWY}$). The provided range of 0 to 1 per HWY is consistent with its high efficacy.

Statement 2: Norplant

Norplant refers to a type of contraceptive implant. Modern implants have extremely low failure rates, typically ranging from 0.05 to 0.3 pregnancies per 100 woman-years ($\approx 0.05-0.3 \text{ per HWY}$). The stated range of 0-1 per HWY accurately reflects this.

Statement 3: LNG-IUS

LNG-IUS stands for Levonorgestrel-releasing intrauterine system. These devices are highly effective, with typical failure rates around 0.1-0.2 pregnancies per 100 woman-years ($\approx 0.1-0.2 \text{ per HWY}$). The rate of 0.02 per HWY is within the expected range for these highly effective long-acting methods.

Statement 4: Levonorgestrel

Levonorgestrel, when referring to methods like Progestin-Only Pills (POPs) used typically, has a higher failure rate (around 7-9 per 100 woman-years). Emergency contraception effectiveness is also measured differently. A rate of 3 per HWY is significantly higher than the rates for DMPA, Norplant, and LNG-IUS, making this statement likely incorrect in the context of comparing highly effective long-term methods.

Conclusion on Correct Statements

Based on the typical failure rates:

• Statement 1 is correct.
• Statement 2 is correct.
• Statement 3 is correct.
• Statement 4 is likely incorrect as it represents a substantially higher failure rate compared to the other methods listed.

Therefore, the correct combination includes statements 1, 2, and 3.