From the Research
The Mirena IUD contains only the progestin levonorgestrel and no estrogen, making it a 100% progestin-based IUD with 0% estrogen content. Specifically, the Mirena IUD contains 52 mg of levonorgestrel (a synthetic progestin) that is released at an initial rate of about 20 micrograms per day, which gradually decreases to about 10 micrograms per day after 5 years 1. This information is based on the most recent and highest quality study available, which evaluated the efficacy and safety of the 52-mg levonorgestrel-releasing intrauterine system for up to 8 years 1. The absence of estrogen is beneficial for women who cannot use estrogen-containing contraceptives due to conditions like history of blood clots, certain types of migraines, or other estrogen-sensitive conditions. The progestin works locally in the uterus to thicken cervical mucus (preventing sperm entry), thin the uterine lining (reducing likelihood of implantation), and partially suppressing ovulation in some users. The predominantly local action of the hormone means that systemic side effects are typically less pronounced than with combined hormonal contraceptives that contain both estrogen and progestin.
Some key points to consider:
- The Mirena IUD is a highly effective, long-term, safe, reversible contraceptive option 2
- It is approved for 5 years of contraceptive use, and there is evidence that it can be effective for up to 7 years of continuous use 2
- The device's strong local effects on the endometrium benefit women with various benign gynecological conditions such as menorrhagia, dysmenorrhea, leiomyomata, adenomyosis, and endometriosis 2
- The 52-mg levonorgestrel-releasing intrauterine system maintains high contraceptive efficacy, user satisfaction, and a favorable safety profile through 8 years of use 1
Overall, the Mirena IUD is a highly effective and safe contraceptive option that contains only progestin and no estrogen, making it a good choice for women who cannot use estrogen-containing contraceptives.