What Is It?

The intrauterine device (IUD) is a T-shaped piece of plastic about the size of a quarter that is placed inside the uterus to prevent pregnancy. Two types of IUDs are available:

  • Mirena IUD = Uses hormones
  • Paragard IUD = Uses copper

You should discuss with your doctor what type of IUD is right for you.

How Does It Work?

The copper-coated IUD primarily prevents pregnancy by not allowing the sperm to fertilize the egg. It may also make it harder for a fertilized egg to implant in the uterus. When an IUD is coated with progesterone, it works in a similar way, but may also thicken the cervical mucus, which prevents sperm from entering the uterus and possibly prevent ovulation (the release of an egg during the monthly cycle).

How Well Does It Work?
Over the course of 1 year, fewer than 1 out of 100 typical couples using an IUD will have an accidental pregnancy. In fact, studies indicate that the IUD is one of the most effective and safest methods of birth control. Although the IUD is an effective method of birth control, it can come out of place and therefore should be checked regularly to be sure it is in place.

In general, how well each type of birth control method works depends on a lot of things. These include whether a person has any health conditions or is taking any medications or herbal supplements that might interfere with its use. The copper IUD allows some flexibility for women who cannot use a hormonal method of birth control (such as the Pill, ring, or patch). The IUD can also provide a long-term form of birth control.

Protection Against STDs
The IUD does not protect against sexually transmitted diseases (STDs). For those having sex, condoms must always be used along with the IUD to protect against STDs. One of the concerns with the IUD is that women who have multiple partners and do not use condoms can be at greater risk for STDs, and there’s the possibility that these diseases could develop into a pelvic infection. This is true, though, for all methods of birth control. Abstinence (not having sex) is the only method that always prevents pregnancy and STDs.

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