
Among different forms of contraception, IUDs, or intrauterine devices are considered as effective, convenient and safe. Hormonal IUDs with levonorgestrel, a synthetic form of progesterone, a hormone naturally produced by the ovaries are among the popular choices. These contraceptive devices are inserted into the uterus to prevent pregnancy. Following subsections offer a detailed look at hormonal IUDs, including information to answer the common question Mirena, Kyleena, Skyla & Liletta – What’s the difference? All the four hormonal IUDs belong to the same overall category with certain differences among each.
Overview of hormonal IUDs Mirena, Kyleena, Skyla, and Liletta
- Mirena releases levonorgestrel and is approved for up to 5 years of use. This IUD is highly effective at preventing pregnancy, with a failure rate of less than 1% in typical use. It works by thickening the cervical mucus, preventing sperm from reaching the egg. It also thins the lining of the uterus, making it less receptive to implantation. Mirena may also inhibit ovulation in some women, further reducing the chances of pregnancy. Additionally, the IUD is FDA-approved for the treatment of heavy menstrual bleeding.
- Kyleena, another hormonal IUD that releases levonorgestrel is approved for up to 5 years of use. Similar to Mirena, but with a lower hormone dose Kyleena works similarly as Mirena, thickening cervical mucus, thinning the uterine lining, and potentially inhibiting ovulation. Kyleena is intended for women who have not given birth or have a smaller uterus, as it is smaller in size compared to Mirena.
- Skyla is approved for up to 3 years of use and is specifically designed for women who have not given birth or have a smaller uterus. It is smaller in size compared to Mirena and Kyleena. Skyla works similarly to the other hormonal IUDs, thickening cervical mucus, thinning the uterine lining, and potentially inhibiting ovulation.
- Liletta is another hormonal IUD that releases levonorgestrel and is approved for up to 6 years of use. Liletta is similar in size and hormone dosage to Mirena, offering a cost-effective option for long-term contraception.
IUDs with levonorgestrel offer several advantages including the high efficacy at preventing pregnancy, apart from being long-lasting. The reversible nature of these contraceptives make them more appealing and convenient for couples. Hormonal IUDs do not require daily or frequent administration, and also do not interfere with sexual spontaneity. These contraceptives are especially suitable for women who cannot or prefer not to use hormonal contraceptives in pill or patch form.
On the downside, IUDs with levonorgestrel do not protect against sexually transmitted infections, and it may be necessary to look at additional barrier methods to prevent STI.
How does levonorgestrel work?
As a synthetic form of the hormone progesterone, Levonorgestrel works primarily by exerting its effects on the reproductive system, influencing various processes involved in fertility and pregnancy, as outlined below:
- Thickening of Cervical Mucus: Levonorgestrel thickens the cervical mucus, making it more viscous and creating a barrier for sperm. This thicker mucus makes it difficult for sperm to swim through the cervix and reach the uterus, reducing the chances of fertilization.
- Inhibition of Ovulation: Levonorgestrel suppresses or inhibits ovulation in some women. By inhibiting the release of an egg from the ovary, levonorgestrel prevents fertilization from occurring. However, ovulation suppression is not the primary mechanism of action for hormonal IUDs like Mirena, Kyleena, Skyla, and Liletta, with the primary mechanism of actioning being the thickening of cervical mucus and thinning of the uterine lining.
- Thinning of the Uterine Lining: Levonorgestrel thins the lining of the uterus, known as the endometrium. This thinning makes the uterine environment less receptive to implantation, which is the attachment of a fertilized egg to the uterine wall. By reducing the likelihood of successful implantation, levonorgestrel helps prevent pregnancy.
The actual mechanisms of action of levonorgestrel may vary among different forms of administration. For instance, emergency contraceptive pills containing levonorgestrel, commonly known as “morning-after pills,” primarily work by delaying or inhibiting ovulation if taken before ovulation occurs. These pills are designed to be used within a few days after unprotected intercourse to reduce the risk of pregnancy.
Mirena, Kyleena, Skyla & Liletta – What’s the difference?
With all the background information about IUDs, it is now time to answer the above question. Mirena, Kyleena, Skyla, and Liletta are all hormonal intrauterine devices containing levonorgestrel; however, there are key differences among them, as listed below:
- Hormone Dosage: Mirena contains the highest dose of levonorgestrel among these IUDs. Kyleena and Liletta have a slightly lower hormone dosage compared to Mirena, while Skyla has the lowest hormone dose. The differences in hormone dosage may affect factors such as bleeding patterns and side effects.
- Approved Duration of Use: The approved duration of use varies for each IUD. Mirena is approved for up to 5 years, Kyleena for up to 5 years, Skyla for up to 3 years, and Liletta for up to 6 years. The duration of use may impact contraceptive needs and preferences, as well as when the IUD needs to be replaced.
- Size and Design: The size and design of the IUDs differ, which can affect their suitability for certain individuals. Skyla is the smallest in size and is specifically designed for women who have not given birth or have a smaller uterus. Mirena, Kyleena, and Liletta are larger in size and may be suitable for women who have given birth or have a larger uterus.
- Indications and Approved Uses: While all these IUDs are primarily used for contraception, Mirena has an additional approved use for the treatment of heavy menstrual bleeding. It has been specifically studied and approved for this indication. The other IUDs may also help reduce menstrual bleeding but may not have specific approvals for that purpose.
- Availability and Cost: Availability and cost may vary among these IUDs based on factors such as healthcare coverage, geographical location, and healthcare provider preferences.
The choice of IUD depends on various factors, including personal preferences, medical history, and a proper assessment by a specialist healthcare provider.