Intrauterine Device (IUD) for birth control
An IUD is a small, T-shaped plastic device that is wrapped in copper or contains hormones. The IUD is inserted into your uterus by your doctor. A plastic string tied to the end of the IUD hangs down through the cervix into the vagina. You can check that the IUD is in place by feeling for this string. The string is also used by your doctor to remove the IUD.
Types of IUDs
- Hormonal IUD. The hormonal IUD, such as Mirena, releases levonorgestrel, which is a form of the hormone progestin. The hormonal IUD appears to be slightly more effective at preventing pregnancy than the copper IUD. The hormonal IUD is effective for at least 5 years.
- Copper IUD. The most commonly used IUD is the copper IUD (such as Paragard). Copper wire is wound around the stem of the T-shaped IUD. The copper IUD can stay in place for at least 10 years and is a highly effective form of contraception.
How it works
Both types of IUD prevent fertilization of the egg by damaging or killing sperm. The IUD also affects the uterine lining — where a fertilized egg would implant and grow.
This IUD prevents fertilization by damaging or killing sperm and making the mucus in the cervix thick and sticky, so sperm can't get through to the uterus. It also keeps the lining of the uterus (endometrium) from growing very thick.1 This makes the lining a poor place for a fertilized egg to implant and grow. The hormones in this IUD also reduce menstrual bleeding and cramping.
Copper is toxic to sperm. It makes the uterus and fallopian tubes produce fluid that kills sperm. This fluid contains white blood cells, copper ions, enzymes, and prostaglandins.
Insertion
You can have an IUD inserted at any time, as long as you are not pregnant. An IUD is inserted into your uterus by your doctor. The insertion procedure takes only a few minutes and can be done in a doctor's office. Sometimes a local anesthetic is injected into the area around the cervix, but this is not always needed.
What to expect after treatment
You may want to have someone drive you home after the insertion procedure. You may experience some mild cramping and light bleeding or spotting for 1 or 2 days.
Follow-up
Your doctor may want to see you 4 to 6 weeks after the IUD insertion, to make sure it is in place.
You may be a good candidate for an IUD if you:
- Do not have a pelvic infection at the time of IUD insertion.
- Have only one sex partner who does not have other sex partners and who is infection-free. This means you are not at high risk for sexually transmitted infections (STIs) or pelvic inflammatory disease (PID), or you and your partner are willing to also use condoms.
- Want an effective, long-acting method of birth control that requires little effort and is easily reversible.
- Cannot or do not want to use birth control pills or other hormonal birth control methods.
- Are breast-feeding.
How well it works
The IUD is a highly effective method of birth control.
- When using the hormonal IUD, about 2 out of 1,000 women become pregnant in the first year.
- When using the copper IUD, about 6 out of 1,000 women become pregnant in the first year.
- Most pregnancies that occur with IUD use happen because the IUD is pushed out of, or expelled from, the uterus unnoticed. IUDs are most likely to come out in the first few months of IUD use, after being inserted just after childbirth, or in women who have not had a baby.
Advantages of IUDs include cost-effectiveness over time, ease of use, lower risk of ectopic pregnancy, and no interruption of foreplay or intercourse.
Other advantages of the hormonal IUD include:
- Reduces heavy menstrual bleeding by an average of 90% after the first few months of use.
- Reduces menstrual bleeding and cramps and, in many women, eventually causes menstrual periods to stop altogether. In this case, not menstruating is not harmful.
- May prevent endometrial hyperplasia or endometrial cancer.
- May effectively relieve endometriosis and is less likely to cause side effects than high-dose progestin.
- Reduces the risk of ectopic pregnancy.
- Does not cause weight gain.
Risks
Risks of using an intrauterine device (IUD) include:
- Menstrual problems. The copper IUD may increase menstrual bleeding or cramps. Women may also experience spotting between periods. The hormonal IUD may reduce menstrual cramps and bleeding.
- Perforation. In 1 out of 1,000 women, the IUD will get stuck in or puncture (perforate) the uterus. Although perforation is rare, it almost always occurs during insertion. The IUD should be removed if the uterus has been perforated.
- Expulsion. About 2 to 10 out of 100 IUDs are pushed out or expelled from the uterus into the vagina during the first year. This usually happens in the first few months of use. Expulsion is more likely when the IUD is inserted right after childbirth or in a woman who has not carried a pregnancy. When an IUD has been expelled, you are no longer protected against pregnancy.
