In a small number of people, an IUD can slip partly or completely out of the uterus. If this happens, it is possible to become pregnant.

IUDs are more than 99% effective. This means that less than 1 out of every 100 people who have an IUD will become pregnant.

All IUDs — hormonal, nonhormonal, or copper — have a similar failure rate.

Read on to learn why this happens, your options for emergency contraception, when to take a pregnancy test, and more.

Between 2% and 10% of people with an IUD may experience it slipping partly or completely out of the uterus within the first year of having it inserted. If this happens, you can get pregnant. And you might not realize the IUD has fallen out of place.

In other cases, pregnancy can happen because the IUD hasn’t started to work. The copper IUD, Paragard, protects against pregnancy immediately. But hormonal IUDs, such as Mirena and Skyla, can take up to 7 days to become effective. You could get pregnant if you have sex without a condom or other form of protection during this window.

You may also experience IUD failure if the IUD has been in place for longer than the manufacturer recommends.

Although an older study found that Mirena may protect against pregnancy for a full year after its expiration date, more research is needed to confirm this finding.

If you suspect that your IUD has failed and have had intercourse in the last 72 hours, talk with a doctor or other healthcare professional about using emergency contraception (EC).

EC will stop you from ovulating and prevent you from getting pregnant if your IUD has failed. It won’t end a developing pregnancy.

Your healthcare professional may recommend one of the following options:

Hormonal pills

As a rule of thumb, hormonal EC is most effective when taken within 72 hours of birth control failure. However, you can still take hormonal EC for up to 5 days afterward.

You can purchase EC pills over the counter at your local pharmacy. If you have insurance, you may consider calling your doctor to get a prescription. EC is considered preventive care, so you may be able to fill your prescription for free. If you don’t have insurance, you may have access to a financial assistance program.

Copper IUD

If you have a hormonal IUD and suspect that it’s failed, ask your doctor about switching to a copper IUD. The copper IUD can prevent pregnancy if it’s inserted within 5 days of birth control failure. The copper IUD can stay in for up to 10 years.

As with EC pills, the copper IUD may be available at a reduced rate through your insurance plan. If you don’t have insurance, you may have access to a financial assistance program. Some birth control clinics will offer services even if you can’t pay.

If the pregnancy develops in your uterus, you may notice typical pregnancy symptoms, such as:

  • missed periods
  • nausea, possibly with vomiting
  • sore, enlarged breasts
  • tiredness
  • mild cramps
  • light spotting

Some of these symptoms — like cramping, spotting, and missed periods — can be similar to the side effects of your IUD, so it can be tricky to tell them apart.

If you don’t know what’s causing your symptoms, contact a doctor or other healthcare professional.

Having an IUD in place may be slightly more likely to result in an ectopic pregnancy. This occurs when the embryo implants outside of your uterus.

Symptoms of an ectopic pregnancy include:

  • sharp waves of pain in your abdomen, pelvis, shoulder, or neck
  • severe pain on one side of your abdomen
  • vaginal spotting or bleeding
  • dizziness
  • fainting
  • rectal pressure

An ectopic pregnancy is considered a medical emergency. Seek immediate medical attention if you’re experiencing any of these symptoms.

If you think you might be pregnant, you can take a home pregnancy test. These tests are available over the counter (OTC), and you can use them on the first day of your missed period.

If your IUD has caused your periods to be irregular — or to stop completely — wait 1 to 2 weeks after you suspect your IUD has failed to take an OTC test. These tests are almost 99% accurate. In most cases, a negative result means that you aren’t pregnant. If you’re experiencing unusual symptoms or suspect the test isn’t accurate, contact a doctor.

If the test is positive, make an appointment with an OB-GYN or other healthcare professional. They’ll confirm the results with a urine or blood test and discuss the next steps.

Your doctor will first double-check that you’re pregnant with a urine or blood test.

Pregnancy tests check for human chorionic gonadotropin. Your body only produces this hormone when you’re pregnant.

Your doctor will then do a pelvic exam. According to the American College of Obstetricians and Gynecologists (ACOG), if you become pregnant with an IUD in place, it should be removed if the strings are visible or if it’s located within the cervix.

If your IUD string isn’t visible, they’ll perform an ultrasound to help locate your IUD. They may need to use a cytobrush or other tool to aid in removal.

An ultrasound will also help your doctor determine whether there are problems, such as ectopic pregnancy.

If it’s ectopic, your doctor will recommend medication or surgery to remove the embryo. The exact treatment depends on the embryo’s location and overall development.

IUD pregnancies are slightly more likely to be ectopic (occur outside of the uterus). Ectopic pregnancies sometimes form in the fallopian tubes.

If the pregnancy isn’t removed, the tubes can burst, which can be life threatening.

An ectopic pregnancy that occurs outside of a fallopian tube — in the cervix, for example — is unlikely to grow without endangering your overall health.

Other risks associated with IUD pregnancies include:

It’s also possible that exposure to the hormones in certain IUDs could affect the pregnancy.

There have been reports of fetal developmental issues in live births. For example, exposure to increased levels of progestin has been linked to “increased masculinization of the external genitalia” in female fetuses.

You’ll have to terminate the pregnancy if it’s ectopic. An embryo growing outside the uterus can’t survive. There’s also a significant risk to the pregnant person’s health in an ectopic pregnancy.

Doctors can terminate the pregnancy in one of two ways:

  • If you’re in your first trimester, you can take a medication called methotrexate to stop the embryo from growing. Your body will then absorb the pregnancy tissue.
  • If you’re past your first trimester, you’ll undergo a surgical procedure to remove the ectopic pregnancy.

If the pregnancy is in your uterus, you can decide whether you want to have an abortion. You’ll also want to make sure you understand the laws of your state and how they may affect your choice.

You can take the abortion pill before week 10 of pregnancy. Surgical abortion is available at or after week 10 of pregnancy.

Depending on where you live, you’ll need to follow local law. Abortion laws are more restrictive in some states than others.

If you suspect that your IUD has failed, call your doctor or other healthcare professional right away.

You may be able to take Plan B or another form of EC to prevent pregnancy. If it’s too late to take EC, a medical professional will do an in-office test to determine whether you’re pregnant.

Once you know, you and your doctor can discuss your options.

Although it’s very unlikely, you can get pregnant with an IUD in place. If you think this has happened to you, you can take a home pregnancy test. If it’s positive, make an appointment with a doctor immediately to discuss next steps.