Intrauterine Device

Available as both a hormonal form of birth control and as a non-hormonal form of contraception, using an intrauterine device (more commonly known as an IUD) is one of the most effective birth control methods to prevent pregnancy.

What is It?

An IUD is a small, t-shaped device that is inserted into your uterus by your doctor. It is made out of flexible plastic and contains either copper or hormones. At the end of the IUD are two transparent strings that hang down into the vagina, which women can feel for to check that their IUD is still in place. Depending on the type you use, your IUD can provide you with continuous protection from pregnancy anywhere from five to 12 years.

In the United States, there are two types of IUDs available: the Mirena which continuously releases hormones for up to five years, and the ParaGard Copper T 380A IUD which contains copper and can be worn for up to 12 years. IUD’s are effective as soon as they are inserted.

How Does it Work?

Both types of IUDs primarily work in the same fashion: by preventing the fertilization of an egg. While experts aren’t exactly sure how, it is suspected that the IUD alters the movement of an egg or sperm making conception difficult. However, ovulation still occurs when you use an IUD.

IUDs that contain hormones also work by thicken a woman’s cervical mucus thereby creating a natural barrier to sperm. As well, the hormones help to alter the uterine lining in order to inhibit implantation of a fertilized egg.

Although copper IUDs also alter the endometrial lining and prevent implantation from occurring, the copper contained within the IUD works to increase the production of prostaglandins, hormones that help support a pregnancy.

While the IUD is very effective at preventing pregnancy, it offers no protection against sexually transmitted diseases. The IUD is generally not recommended for women who have multiple sexual partners.

Advantages of the IUD

Because of the long lasting protection against pregnancy an IUD provides, the IUD is one of the most popular types of birth control throughout the world. Many women like the fact that they do not need to worry about their contraceptive on a regular basis.

Additionally, the IUD gives a woman birth control options if she prefers non-hormonal forms of contraceptives, she can use the copper IUD which in no way interferes with her hormonal levels.

Women who use the Mirena IUD may find that their menstrual periods are lighter and that their cramps are not as severe. About 30% of women using this type of IUD will stop menstruating although their periods should return fairly soon after the IUD is removed.

The copper IUD can also be used as a form of emergency contraceptive. It has been shown to be as much as 99% effective in preventing pregnancy from occurring when it is inserted within five days of having unprotected vaginal intercourse.

IUD Side Effects

The most common side effects associated with the IUD include menstrual irregularities and spotting. Women who use the ParaGard IUD may have anywhere from a 50 to 75% increase in their menstrual flow. This heavy flow may lead to anemia in some women.

Additionally, women using this type of IUD may have more menstrual cramps. Women using the Mirena IUD are likely to experience similar side affects as those associated with the birth control pill. Moreover, some women have found the insertion and removal of an IUD to be painful.

IUD Complications

The IUD has been associated with a number of health risks that, although rare, can occur. IUD problems include:

  • Uterine puncture: Occurs in one to three out of every 1,000 insertions. Usually realized right away. If not, the IUD may migrate to other parts of the body necessitating a surgical removal of the IUD.
  • Expulsion: As much as 7% of all IUDs will be expelled by a woman’s body within the first year, mainly within the first few months. Women who fail to realize that their IUD has been expelled are likely to become pregnant. An expelled IUD accounts for 1/3 of all pregnancies that occur to women using an IUD.
  • Tubal infection: Not common, but the process of inserting an IUD may cause naturally occurring vaginal bacteria or an STD to be pushed up into the uterus leading to infection. Mild cases can be cleared up with antibiotics. In some, more serious cases, the IUD may need to be removed. In very rare, but serious instances, the infection may require surgery and possibly leave a woman sterile. Infections that are left untreated may be fatal.
  • Pregnancy: If you think you are pregnant, you should have your IUD removed. A pregnancy that results while a woman is wearing an IUD increases her risk of en ectopic pregnancy, serious pelvic infection, preterm labor and miscarriage. During the first 12 weeks of pregnancy, a woman who has an IUD in place has a 15 to 50% chance of miscarrying. After this time, the risk goes up to 50%.

Safety of IUDs

Because of past problems with IUDs, many women are concerned about just how safe an IUD is to use. The main culprit behind the tarnished reputation is the Dalkon Shield. This IUD was first put on the market in 1970 but recalled in 1975 because 12 of the IUD’s 2.8 million users had died.

The IUD was pulled off the market and, despite the fact that no other IUDs had been found unsafe, many other IUD manufacturers decided to follow suit for fear of lawsuits. In order to avoid problems in the future, IUD manufacturers have worked to improve the safety of IUDs currently on the market.

The IUD may not be suitable for women who have never been pregnant before due to increased risk of expulsion. This is because of a smaller uterus and difficulty with insertion. Women with multiple sex partners are at a higher risk for STDs.


The IUD has been found to be as much as 99% effective when inserted properly. However, not all women are suited to using an IUD. Women who are at an increased risk of STDs; may be pregnant or are trying to conceive; have HIV or AIDS; a history of certain medical conditions and infections; have a deformed uterus or one that sits too far forward or back in the pelvis; or women that have severe anemia may need to consider using a different birth control method. Discuss the issue with your health care provider.

Women who have not had children can safely use the IUD although some doctors may prefer to not prescribe it as these women’s uteri tend to be smaller and may be more likely to get irritated by an IUD.

Chat with other women about the pros and cons of an IUD in our birth control forum.

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