What Is Mirena Used For?
is an intrauterine contraceptive (IUC) that is used for long-term pregnancy prevention. It is a small, flexible plastic device that contains levonorgestrel (a progesterone hormone). It works for five years, although your healthcare provider can remove it earlier if you desire.
Mirena is not for everyone. Mirena is designed for women who have already had at least one baby and who desire desire long-term (but easily reversible) birth control. Mirena is also approved to treat heavy menstrual bleeding in women who choose intrauterine contraception.
Mirena is very effective at preventing pregnancy. Only 0.1 percent of women will become pregnant while taking Mirena. This is at least as effective as the birth control pill
and much more effective than most other forms of birth control. Mirena is not a permanent form of contraception. After it is removed, 80 percent of women may become pregnant within one year.
It's also important to note that Mirena does not protect against HIV
or other sexually transmitted diseases (STDs).
How Does Mirena Work?
There are two types of intrauterine contraceptives (IUC), non-hormonal copper devices (known as intrauterine devices, or IUDs) and hormonal devices (known as intrauterine systems, or IUSs). Mirena is an IUS, meaning that it contains a hormone and relies on the hormone for preventing pregnancy. Your healthcare provider inserts the device into the uterus, where it can remain for up to five years.
Mirena slowly releases a low level of levonorgestrel (a progesterone hormone). In some women (less than half), Mirena works by stopping ovulation (the maturation and release of eggs from the ovaries). However, for most women, Mirena works in other ways (and ovulation continues as usual). In these women, Mirena alters the cervical mucus (the fluid of the cervix, which is the lower, narrow part of the uterus that is connected to the vagina), making it more difficult for sperm to enter the uterus. Mirena also decreases the ability of sperm to survive in the uterus. Lastly, Mirena alters the lining of the uterus (called the endometrium), making it less receptive to an embryo.