An IUD ranks among the most reliable forms of birth control available today, yet no contraceptive method offers a 100 percent guarantee. Many women assume that once the device is in place, pregnancy is simply off the table. The reality is more nuanced. Pregnancy with an IUD can happen, though it remains uncommon, and understanding why it occurs helps women recognize the warning signs early and respond quickly if it does.
Here we break down how IUDs work, the actual odds of conceiving while using one, the symptoms to watch for, and what steps to take if a positive pregnancy test appears unexpectedly.
What Is an IUD & How Does It Prevent Pregnancy?
An intrauterine device, or IUD, is a small T-shaped device that a doctor inserts into the uterus. Two thin strings hang down through the cervix into the upper vagina, allowing both the patient and her provider to confirm the device remains correctly positioned. The IUD can stay in place anywhere from 3 to 10 years, depending on the brand and type.
There are two main categories of IUDs on the market:
- Hormonal IUDs (such as Mirena, Kyleena, and Skyla) release a small amount of progestin into the uterus. This hormone thickens cervical mucus, thins the uterine lining, and in many cases suppresses ovulation. Hormonal IUDs typically remain effective for three to eight years.
- Copper IUDs (such as Paragard) contain no hormones at all. Instead, copper ions create an environment that is toxic to sperm, preventing fertilization. Copper IUDs are approved for use up to 10 years and also work as emergency contraception when inserted within five days of unprotected sex.
Both types sit inside the uterus and act as a physical and chemical barrier against fertilization or implantation, which is why they rank among the most effective reversible contraceptives on the market.
Can You Get Pregnant With An IUD?
Yes, pregnancy with an IUD is possible, but the odds are low. According to the Centers for Disease Control and Prevention, copper IUDs carry a failure rate of about 0.8 percent, while hormonal IUDs using levonorgestrel fail at a rate between 0.1 and 0.4 percent. Put another way, IUDs are considered more than 99 percent effective at preventing pregnancy, placing them in the same effectiveness tier as permanent sterilization.
Pregnancy while using an IUD tends to happen under specific circumstances rather than randomly. The most common contributing factors include the following.
The IUD Shifts Out Of Position
Doctors refer to this as IUD expulsion. When correctly placed, the device sits at the top of the uterus. If it slips down toward or into the cervix, its ability to block fertilization drops significantly, and pregnancy becomes more likely.
Expulsion happens in roughly 2 to 10 percent of users within the first year after insertion, according to the American College of Obstetricians and Gynecologists. Women who insert an IUD shortly after childbirth or while breastfeeding face a somewhat higher chance of displacement.
The IUD Falls Out Completely
In some cases, the device doesn’t just shift, it exits the body entirely, often without the woman noticing. Checking for the strings periodically is one of the simplest ways to confirm the IUD is still doing its job.
Sexual Activity Right After Insertion
A copper IUD begins working immediately after placement. Hormonal IUDs, however, need about seven days to reach full effectiveness. Unprotected intercourse during that first week carries a higher pregnancy risk, which is why doctors typically recommend backup contraception, such as condoms, during this window.
The Device Has Expired
Every IUD comes with a labeled expiration window. Leaving it in longer than recommended slightly raises the chance of failure, since the hormone reservoir or copper effectiveness diminishes over time.
Early Signs of Pregnancy While Using an IUD
Pregnancy symptoms don’t change just because an IUD is in place. Women who conceive while using one may notice:
- A missed or unusually light period
- Breast tenderness or swelling
- Nausea, particularly in the morning
- Unusual fatigue
- Increased urination
- Food cravings or sudden aversions
- Mild cramping
One additional clue specific to IUD users is a change in the strings. If they suddenly feel shorter, longer, or impossible to locate, that can indicate the device has moved, which raises the likelihood that a positive pregnancy test is connected to actual conception rather than a false alarm.
Why Ectopic Pregnancy Risk Increases With an IUD?
This is arguably the most important safety consideration tied to IUD pregnancy. Because the device is specifically designed to prevent implantation inside the uterus, a pregnancy that manages to occur is statistically more likely to implant somewhere else, most often in the fallopian tubes. This is known as an ectopic pregnancy.
It’s worth noting that having an IUD does not raise a woman’s overall lifetime risk of ectopic pregnancy. It simply means that if pregnancy does occur despite the IUD, a higher proportion of those pregnancies turn out to be ectopic rather than uterine.
Early ectopic pregnancy symptoms tend to be subtle and can include:
- Mild pelvic or abdominal pain, often on one side
- Light, irregular vaginal bleeding
- Lower back discomfort
As the condition progresses without treatment, symptoms can escalate to:
- Sudden, severe abdominal or pelvic pain
- Shoulder pain
- Dizziness, fainting, or a rapid heartbeat
- Signs of shock, such as clammy skin or shallow breathing
An ectopic pregnancy cannot continue safely and requires prompt medical treatment, since the growing tissue can rupture the fallopian tube and cause internal bleeding. Any woman with an IUD who experiences these symptoms alongside a positive pregnancy test should seek emergency care immediately.
Other Risks If Pregnancy Continues With an IUD Still in Place
Beyond the risk of ectopic pregnancy, leaving an IUD in during an intrauterine pregnancy raises the likelihood of several complications, including:
- Miscarriage. A large retrospective study tracking over 220,000 deliveries found pregnancy loss occurred in about 2 percent of cases where the IUD stayed in place, compared with roughly 0.5 percent when no IUD was present.
- Preterm birth. The same research linked retained IUDs to preterm delivery rates near 14 percent, more than double the rate seen in pregnancies without an IUD.
- Infection. Bacterial infection risk was notably higher when an IUD remained in the uterus throughout pregnancy.
- Low birth weight. Babies born to mothers who kept an IUD in place during pregnancy showed a slightly elevated risk of low birth weight.
For these reasons, doctors generally recommend removing the IUD as early as possible once an intrauterine pregnancy is confirmed, particularly when the strings are visible or the device is accessible near the cervix.
What to Do If You Think You’re Pregnant With an IUD?
Anyone who suspects pregnancy while using an IUD should take these steps without delay.
- Take a home pregnancy test. These tests remain accurate regardless of IUD use, since they detect hCG hormone levels rather than physical conception markers.
- Contact a doctor immediately after a positive result. Prompt evaluation matters because of the elevated ectopic pregnancy risk associated with IUD failure.
- Expect a pelvic exam and possibly an ultrasound. This helps the provider locate both the pregnancy and the IUD, confirming whether the pregnancy is intrauterine or ectopic.
- Discuss removal versus retention. If the strings are visible and the pregnancy is intrauterine, the doctor will usually recommend gentle removal to lower the risk of miscarriage and infection. If the device sits too high or removal seems risky, the provider may choose to leave it in place and monitor the pregnancy closely.
- Follow up regularly. Additional ultrasounds and hormone level checks help confirm the pregnancy is progressing normally and that no complications are developing.
Every situation is different, and the right path forward depends on gestational age, the position of the IUD, and the individual’s personal wishes regarding the pregnancy.
Frequently Asked Questions
How likely is it to get pregnant with an IUD?
It’s uncommon. Copper IUDs fail at a rate of about 0.8 percent per year, while hormonal IUDs fail at a rate between 0.1 and 0.4 percent, according to CDC data. That makes IUDs over 99 percent effective overall.
How soon can you get pregnant after IUD removal?
Fertility typically returns quickly. IUDs do not suppress ovulation the way some other hormonal methods do, so pregnancy can occur within days or weeks of removal, depending on the individual’s cycle and timing of intercourse.
Can you get pregnant with a copper IUD?
Yes, though it’s rare. Copper IUDs remain highly effective, but expulsion, displacement, or expiration of the device can still allow pregnancy to occur.
Can you get pregnant with an expired IUD?
It’s possible. Once an IUD passes its approved timeframe, its hormone supply or copper effectiveness declines, which slightly raises the risk of pregnancy compared with a device still within its labeled window.
Does having an IUD increase the risk of ectopic pregnancy overall?
No. An IUD does not raise a woman’s general risk of ectopic pregnancy. It only means that in the rare event pregnancy does occur despite the IUD, that pregnancy is more likely to be ectopic than uterine, since the device specifically blocks implantation inside the uterus.
What are the first signs of pregnancy with an IUD?
The signs mirror typical early pregnancy symptoms: a missed period, breast tenderness, nausea, fatigue, and frequent urination. Missing, shortened, or lengthened IUD strings can be an additional clue that the device has shifted.
Key Takeaway
IUDs remain one of the most dependable forms of birth control available, but “highly effective” doesn’t mean “impossible to fail.” Recognizing the early symptoms of pregnancy, checking IUD strings periodically, and reaching out to a doctor immediately after any positive test result are the best ways to protect both fertility and overall health if pregnancy does occur unexpectedly.
References
- Centers for Disease Control and Prevention. “Contraception.” CDC Division of Reproductive Health.
https://www.cdc.gov/reproductivehealth/contraception/index.htm - American College of Obstetricians and Gynecologists. “Long-Acting Reversible Contraception (LARC): Intrauterine Device (IUD) and Implant.”
https://www.acog.org/womens-health/faqs/long-acting-reversible-contraception-iud-and-implant - Planned Parenthood. “IUD Birth Control.”
https://www.plannedparenthood.org/learn/birth-control/iud - American College of Obstetricians and Gynecologists. “Ectopic Pregnancy.”
https://www.acog.org/womens-health/faqs/ectopic-pregnancy
