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
Types of IUDs
Hormonal IUD. The hormonal IUD, such as Mirena or Skyla, 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. There are two hormonal IUDs—one works for 5 years, and the other works for 3 years.
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
up to 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).
Hormonal IUD. 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
Copper IUD. 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
You can have an IUD inserted at any
time, as long as you are not pregnant and you don't have a pelvic infection. 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.
IUD insertion is easiest in
women who have had a vaginal childbirth in the past.
may have you feel for the IUD string right after insertion, to be sure you know
what it feels like.
You may want to have someone drive you
home after the insertion procedure. You may experience some mild cramping and
light bleeding (spotting) for 1 or 2 days.
Do not have sex, use tampons, or put anything in your vagina for the first 24 hours after you have an IUD inserted.2
Your doctor may want to see you 4 to 6
weeks after the IUD insertion, to make sure it is in place.
sure to check the string of your IUD after every period. To do this, insert a
finger into your vagina and feel for the cervix, which is at the top of the
vagina and feels harder than the rest of your vagina (some women say it feels
like the tip of your nose). You should be able to feel the thin, plastic string
coming out of the opening of your cervix. It may coil around the cervix, which
can make it difficult to find. Call your doctor if you cannot feel the string
or the rigid end of the IUD.
If you cannot feel the string, it
doesn't necessarily mean that the IUD has been expelled. Sometimes the string
is just difficult to feel or has been pulled up into the cervical canal (which
will not harm you). An exam and sometimes an
ultrasound will show whether the IUD is still in
place. Use another form of birth control until your doctor makes sure that the
IUD is still in place.
If you have no problems, check the string
after each period and return to your doctor once a year for a checkup.
You may be a good candidate for an IUD
- Do not have a pelvic infection at the time of
- 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
- Cannot or do not want to use birth control pills or
other hormonal birth control methods.
- Are breast-feeding.
The copper IUD is recommended for
emergency contraception if you have had unprotected
sex in the past few days and need to avoid pregnancy and
you plan to continue using the IUD for birth control. As a short-term type of
emergency contraception, the copper IUD is more expensive than emergency
contraception with hormone pills.
The IUD is a highly effective method
of birth control.
- When using the hormonal or copper IUD, fewer than 1 woman out of 100 becomes pregnant in the first year.3
- Most pregnancies
that occur with IUD use happen because the IUD is pushed out of (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
Other advantages of the hormonal IUD
the hormonal IUD:
- Reduces heavy menstrual bleeding by an
average of 90% after the first few months of use.1
- 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
endometriosis and is less likely to cause side effects
than high-dose progestin.4
- Reduces the
- Does not cause weight
Risks of using an intrauterine device (IUD)
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.1
Perforation. In 1 out of 1,000 women, the IUD will get stuck
in or puncture (perforate) the uterus.1 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 (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.1 When an IUD has been expelled, you are no longer protected
Disadvantages of IUDs include the high cost of insertion,
no protection against STIs, and the need to be removed by a doctor.
Disadvantages of the hormonal IUD
The hormonal IUD may cause
noncancerous (benign) growths called
ovarian cysts, which usually go away on their
The hormonal IUD can cause hormonal side effects similar to those
caused by oral contraceptives, such as breast tenderness, mood swings,
headaches, and acne. This is rare. When side effects do happen, they usually go
away after the first few months.
Pregnancy with an IUD
If you become pregnant with an IUD in place, your doctor will recommend
that the IUD be removed. This is because the IUD can cause
preterm birth (the IUD will not cause birth defects).
When to call your doctor
When using an IUD, be
aware of warning signs of a more serious problem related to the IUD.
Call your doctor now or seek immediate medical care if:
- You have severe pain in your belly or pelvis.
- You have severe vaginal bleeding.
- You are passing clots of blood and soaking through your usual pads or tampons each hour for 2 or more hours.
- You have vaginal discharge that smells bad.
You have a fever and chills.
- You think you might be pregnant.
Watch closely for changes in your health, and be sure to contact your doctor if:
- You cannot find the string of your IUD, or the string is shorter or longer than normal.
- You have any problems with your birth control method.
- You think you may have been exposed to or have a sexually transmitted infection.
The IUD is most likely to work well
for women who have been pregnant before. Women who have never been pregnant are
more likely to have pain and cramping after the IUD is inserted. They are also more likely to expel the IUD.
But they can still use the IUD.
Pelvic inflammatory disease (PID) concerns have been
linked to the IUD for years. But it is now known that the IUD itself does not
cause PID. Instead, if you have a genital infection when an IUD is inserted,
the infection can be carried into your uterus and fallopian tubes. If you are
at risk for a
sexually transmitted infection (STI), your doctor will
test you and treat you if necessary, before you get an IUD.
Intrauterine devices reduce the risk of all pregnancies, including
ectopic (tubal) pregnancy. But if a pregnancy does
occur while an IUD is in place, it is a little more likely that the pregnancy
will be ectopic. Ectopic pregnancies require medicine or surgery to remove the
pregnancy. Sometimes the fallopian tube on that side must be removed as
IUD use and medical conditions
An IUD can be a
safe birth control choice for women who:5
- Have a history of
ectopic pregnancy. Both the copper IUD and hormonal IUD are
- Have a history of irregular menstrual bleeding and
pain. The hormonal IUD may be appropriate for these women and for women who have a
bleeding disorder or those who take blood thinners
- Have a history of
endometriosis. The hormonal IUD is a good choice for women
who have endometriosis.
Complete the special treatment information form (PDF) (What is a PDF document?) to help you understand this treatment.
Grimes DA (2007). Intrauterine devices (IUDs). In RA
Hatcher et al., eds., Contraceptive Technology, 19th
ed., pp. 117–143. New York: Ardent Media.
Dean G, Schwarz EB (2011). Intrauterine contraceptives (IUCs). In RA Hatcher et al., eds., Contraceptive Technology, revised 20th ed., pp. 147–191. New York: Ardent Media.
Trussell J, Guthrie KA (2011). Choosing a contraceptive: Efficacy, safety, and personal considerations. In RA Hatcher et al., eds., Contraceptive Technology, 20th ed., pp. 45–74. Atlanta: Ardent Media.
Fritz MA, Speroff L (2011). Endometriosis. In Clinical Gynecologic Endocrinology and Infertility, 8th ed., pp. 1221–1248. Philadelphia: Lippincott Williams and Wilkins.
Speroff L, Darney PD (2011). Intrauterine contraception. In A Clinical Guide for Contraception, 5th ed., pp. 239–279. Philadelphia: Lippincott Williams and Wilkins.