Intrauterine Devices (IUDs)
An intrauterine device (IUD) is one form of pharmaceutical birth control. While not the most popular form of birth control, IUDs are the most effective form of contraceptive.
IUD failure rates are 0.8 percent for copper IUDs, and 0.2 percent for hormonal IUDs. These are significantly lower than failure rates for other hormonal methods of contraception, including pills, patches, and shots, which range from 5 – 9 percent failure.
While IUDs are generally safe to use, some women may experience severe side effects and complications, and should be aware of any symptoms that could be warning signs of serious problems. See all Mirena side effects here.
Types of IUD
There are two types of IUDs: copper and hormonal. Both IUD types are popular in the U.S. due to their low maintenance and long efficacy in preventing pregnancy.
Both hormonal and copper IUDs are implanted in the uterus, where they remain for the duration of their use (or until removed due to complications). Once an IUD is inserted, there is no need to take a daily pill, though other contraceptive methods (condoms, spermicide, etc.) can still be employed to increase effectiveness. IUDs offer long-term benefits by preventing pregnancy from 5 – 12 years, depending on the type.
Hormone-based intrauterine devices use progestin, a synthetic version of the human hormone progesterone, to prevent pregnancy. Specifically, progestin inhibits egg fertilization in three ways:
- Thickening cervical mucus to trap or block sperm
- Thinning the uterine wall to prevent egg attachment
- Preventing ovulation so that no egg is released for the sperm to reach
There are currently four brands of hormonal IUD approved by the U.S. Food & Drug Administration. Three of these – Mirena, Kyleena and Skyla – are produced and marketed by Bayer pharmaceuticals. The primary difference between each of these three IUDs is the amount of progestin (levonorgestrel) each one releases.
Hormonal IUD Comparison
|Mirena||Kyleena||Skyla & Liletta|
|Duration: Up to 5 years|
|Duration: Up to 5 years|
|Duration: Up to 3 years|
Hormonal IUDs can be removed at any time, such as if the woman wants to become pregnant or if there are complications or side effects from the device.
Copper intrauterine devices, sometimes known as intrauterine coils, do not use any hormones. Rather, the copper in the IUD acts a spermicide, and it may also help to impede implantation of the fertilized eggs.
The only copper IUD approved by the FDA is ParaGard. It is effective as a contraceptive for up to 10 years, with some studies showing effectiveness for as long as 12 years. Like hormonal IUDs, copper IUDs can be removed at any time.
IUD Safety Concerns
As with many types of medical devices, IUDs carry with them a unique set of safety issues. These can come in the form of severe side effects and complications, as well as misconceptions about the device that can lead to unsafe practices or uses. Read about common birth control myths.
Some existing medical or physiological conditions can increase the likelihood of IUD complications or ineffectiveness. These include:
- Sexually transmitted diseases (STDs)
- Pelvic infections (especially within 3 months of childbirth or an abortion)
- Untreated cervical or uterine cancer
- Vaginal bleeding (excluding menstruation)
In addition to the potential for complications, some people may misunderstand the purpose of IUDs. For example, IUDs will not protect against sexually transmitted diseases or infections, so other prophylactic precautions should be made to prevent such transmissions.