**Question:** Contraceptive LNG-IUD (levonorgestrel intra-uterine device) has a cumulative pregnancy rate of:

A. 0%
B. 1%
C. 2%
D. 5%

**Core Concept:**
The levonorgestrel intrauterine device (LNG-IUD) is a type of long-acting reversible contraceptive method. It releases levonorgestrel, a synthetic progestin hormone, into the uterine cavity. This hormone works systemically, suppressing ovulation and thickening the cervical mucus, making it difficult for sperm to reach the ovum. Over time, the cumulative pregnancy rate is determined by assessing the number of unplanned pregnancies among users.

**Why the Correct Answer is Right:**
The correct answer is **B. 1%**. This indicates that among the users of LNG-IUD, only 1% experience an unplanned pregnancy over a 5-year period.

**Why Each Wrong Option is Incorrect:**
A. 0% - This is incorrect because, despite being an effective contraceptive method, LNG-IUDs are not 100% effective.
C. 2% - This value is slightly higher than the correct answer but still inaccurate.
D. 5% - This option is too high, indicating lower effectiveness than the correct answer.

**Why the Correct Answer is Right:**
Levonorgestrel-releasing intrauterine devices (LNG-IUDs) are considered highly effective contraceptives, with a failure rate of around 1%. The low failure rate is due to the combination of hormonal and mechanical contraceptive mechanisms:

1. Hormonal: Levonorgestrel suppresses ovulation and thickens cervical mucus, making it difficult for sperm to reach the ovum.
2. Mechanical: The LNG-IUD physically prevents implantation of a fertilized egg in the uterine lining.

**Clinical Pearl:**
While LNG-IUDs are highly effective, it is essential to counsel patients about the possibility of unplanned pregnancy and recommend additional barrier methods (condoms) for added protection. This combination approach increases the overall effectiveness of contraception and reduces the risk of pregnancy, ensuring a better risk-benefit profile for patients.