Hormonal IUD (Mirena)
Mirena is a hormonal intrauterine device (IUD) that can provide long-term birth control (contraception).
The device is a T-shaped plastic frame that’s inserted into the uterus, where it releases a type of the hormone progestin. To prevent pregnancy, Mirena:
Thickens mucus in the cervix to stop sperm from reaching or fertilizing an egg
Thins the lining of the uterus and partially suppresses ovulation
Mirena prevents pregnancy for up to five years after insertion. It’s one of several hormonal IUDs with Food and Drug Administration approval.
Why it’s done
Mirena offers effective, long-term contraception. It can be used in premenopausal women of all ages, including teenagers.
Among various benefits, Mirena:
Eliminates the need to interrupt sex for contraception
Doesn’t require partner participation
Can remain in place for up to five years
Can be removed at any time, followed by a quick return to your normal fertility
Can be used while breast-feeding — although your health care provider will likely recommend waiting six to eight weeks after childbirth because earlier placement increases the risk of injuring the uterus during placement
Doesn’t carry the risk of side effects related to birth control methods containing estrogen
Mirena can decrease menstrual bleeding after three or more months of use. About 20 percent of women stop having periods after one year of using Mirena.
Mirena can also decrease:
Severe menstrual pain and pain related to the abnormal growth of uterine-lining tissue outside the uterus (endometriosis)
The risk of pelvic infection
The risk of endometrial cancer
Because of these noncontraceptive benefits, Mirena is often prescribed for women with:
Heavy menstrual bleeding
Cramping or pain with periods
Abnormal growth of the lining of the uterus (endometrial hyperplasia)
Abnormal growth of uterine-lining tissue into the muscular wall of the uterus (adenomyosis)
Mirena isn’t appropriate for everyone. Your health care provider may discourage use of Mirena if you have:
Breast cancer, or have had it
Uterine or cervical cancer
Uterine abnormalities, such as fibroids, that interfere with the placement or retention of Mirena
A pelvic infection or current pelvic inflammatory disease
Unexplained vaginal bleeding
Tell your health care provider if you:
Take any medications, including nonprescription and herbal products
Have diabetes or high blood pressure
Have a heart condition or have had a heart attack
Have blood-clotting problems or have had a stroke
Recently gave birth or are breast-feeding
Less than 1 percent of women who use Mirena will get pregnant in a year of typical use.
If you do conceive while using Mirena, you’re at higher risk of an ectopic pregnancy — when the fertilized egg implants outside the uterus, usually in a fallopian tube. However, because Mirena prevents most pregnancies, women who use it are at lower risk of having an ectopic pregnancy than are other sexually active women who are not using contraception.
Mirena is generally safe. But it’s important to remember that:
Mirena doesn’t protect against STIs.
Rarely, insertion of Mirena causes perforation of the uterus. The risk of perforation might be higher when inserted during the postpartum period.
Side effects associated with Mirena include:
Irregular bleeding, which can improve after six months of use
Cramping or pelvic pain
It’s also possible to expel Mirena from your uterus. You may be more likely to expel Mirena if you:
Have never been pregnant
Have heavy or prolonged periods
Have severe menstrual pain
Previously expelled an IUD
Are younger than age 20
Had Mirena inserted immediately after childbirth
Your health care provider may recommend removal of Mirena if you develop:
A pelvic infection
Inflammation of the endometrium (endometritis)
Endometrial or cervical cancer
Pelvic pain or pain during sex
Very severe migraine
A significant increase in blood pressure, or have a stroke or heart attack
Possible exposure to an STI
Mirena can remain in place for up to five years. To remove Mirena, your health care provider will likely use forceps to grasp the device’s strings and gently pull. The device’s arms will fold upward as it’s withdrawn from the uterus.
Light bleeding and cramping is common during removal. Rarely, removal can be more complicated.