Mirena Intrauterine Contraceptive (IUC)
The Mirena Intrauterine Contraceptive (IUC) is a T-shaped device that is inserted into the uterus during a regular speculum exam. The device is usually placed during a period or when there is uterine bleeding because the cervical canal is more open, making insertion easier and less uncomfortable.
There are many theories about how IUCs work. None of them are proven but the most credible are:
- Direct effect on sperm due to thickening of cervical mucus (blocking the sperm highway)
- Direct effect on uterine lining causing cellular changes that are toxic to sperm
- Direct decrease of fertilized eggs due to the sperm killing effects of the Mirena hormones
- Decrease of endometrial lining due to hormonal effects of levonorgestrel , the progesterone hormone in the Mirena
What we do know is that Mirena provides both birth control and a decrease in menstrual flow and other types of uterine bleeding.
Irregular bleeding and increased number of bleeding and spotting days can occur in the first 3-6 months after placement but periods stop completely in 20% of women after the first year!
- Lasts up to 5 years
- Effective immediately
- Failure rate of less than 1% (compared with the 8% failure rate for the pill)
- Reversible treatment with 90% of former users conceiving within the first year after removal
- Reduces menstrual bleeding and pain in women with fibroids
- Periods stop in 20% of users after the first year
- Can be used by breastfeeding mothers
- Requires office visit for placement and removal
- Insertion may be uncomfortable
- Slightly higher risk of uterine infection in the first 20 days after insertion
- Risk of problems with placement including uterine perforation or expulsion
- Irregular bleeding and spotting possible in the first 3-6 months after placement
- Mood-change or depression (especially if patient has a history of similar problems with the pill)
- Weight gain, headache, breast pain, acne, decreased sex drive and high blood pressure in some patients