Can you still fall pregnant with the coil?

October 9, 2025 •

4 min read

Fewer than 1 out of 100 people with an intrauterine device (IUD) get pregnant each year, making it one of the most effective forms of contraception available [1.2.2, 1.3.1]. So, can you still fall pregnant with the coil? While unlikely, it can happen.

Quick Summary

Intrauterine devices (IUDs), or coils, are over 99% effective at preventing pregnancy. However, in rare cases, failure can occur, leading to significant health risks, including ectopic pregnancy.

Key Points

Extremely Rare: Pregnancy with an IUD (coil) is very uncommon, with a failure rate of less than 1% per year [1.2.2].
Ectopic Pregnancy Risk: If pregnancy does occur with an IUD in place, there is a significantly higher risk of it being an ectopic pregnancy, which is a medical emergency [1.6.3, 1.6.4].
Causes of Failure: IUD failure is most often due to the device being expelled from the uterus (expulsion) or moving from its correct position [1.7.2].
Removal is Recommended: If an intrauterine pregnancy occurs and is desired, doctors recommend removing the IUD early to reduce the risk of miscarriage, infection, and preterm birth [1.5.3, 1.9.3].
Types of IUDs: Both hormonal and copper IUDs are over 99% effective, but they work differently and have different side effect profiles [1.3.1].

Understanding IUDs (The Coil)

An intrauterine device (IUD), commonly known as the coil, is a small, T-shaped device inserted into the uterus to provide long-term, reversible birth control [1.11.3]. It's a highly effective method, with a failure rate of less than 1% [1.2.2]. There are two primary types of IUDs available: hormonal and non-hormonal (copper) [1.11.4].

How IUDs Prevent Pregnancy

Both types of IUDs work by creating an environment in the uterus that is inhospitable to sperm, primarily by triggering a localized inflammatory response [1.11.4].

Hormonal IUDs (e.g., Mirena, Kyleena, Liletta, Skyla): These devices release a small amount of the hormone progestin (levonorgestrel) [1.11.4]. This hormone thickens cervical mucus to block sperm from reaching an egg, thins the uterine lining to prevent implantation of a fertilized egg, and can sometimes stop ovulation altogether [1.11.1, 1.11.4]. Depending on the brand, hormonal IUDs are effective for three to eight years [1.10.4].
Copper IUDs (e.g., Paragard): This IUD is hormone-free and instead has copper coiled around the plastic frame [1.11.4]. The copper acts as a natural spermicide, effectively stopping sperm from reaching and fertilizing an egg [1.11.1]. Copper IUDs can prevent pregnancy for up to 10 years and can also be used as a highly effective form of emergency contraception if inserted within five days of unprotected sex [1.3.1, 1.10.4].

Why IUD Failure Happens

Though rare, an IUD can fail to prevent pregnancy. The primary reasons for failure include:

Expulsion: The IUD can slip out of its correct position at the top of the uterus or fall out completely, sometimes without the user noticing [1.7.2, 1.8.1]. Expulsion is more common in the first few months after insertion and happens in about 2-10% of users [1.8.1]. Risk factors for expulsion include being under age 20, having heavy or painful periods, and having the IUD inserted shortly after childbirth [1.7.4, 1.8.3].
Incorrect Placement: If the IUD is not inserted correctly by a healthcare provider, it may not be effective [1.7.2]. A provider will check the placement after insertion, but it's crucial to ensure it was done by an experienced professional.
Uterine Perforation: In extremely rare cases, the IUD can push through the wall of the uterus during insertion [1.11.3]. This is a serious complication that requires medical attention.
Device Expiration: Using an IUD beyond its FDA-approved duration can increase the risk of pregnancy as its effectiveness wanes [1.6.1].

Comparison of Hormonal vs. Copper IUDs


Feature	Hormonal IUD (e.g., Mirena, Liletta)	Copper IUD (Paragard)
Mechanism	Releases progestin to thicken cervical mucus and thin uterine lining [1.11.4].	Copper ions act as a spermicide [1.11.1].
Effectiveness	Over 99% effective; failure rate is about 0.2% [1.3.2, 1.9.3].	Over 99% effective; failure rate is about 0.8% [1.9.3].
Duration	3 to 8 years, depending on the brand [1.10.4].	Up to 10 years [1.10.4].
Effect on Periods	Often makes periods lighter, shorter, or stop completely [1.3.3].	Can make periods heavier and cramping more intense [1.3.3].
Hormones	Yes (Progestin) [1.3.1].	No [1.3.1].
Emergency Use	Some brands (Mirena, Liletta) are effective as EC [1.10.1].	Yes, the most effective form of emergency contraception [1.3.1].

Risks of Getting Pregnant with a Coil

Becoming pregnant with an IUD in place carries significant risks for both the mother and the pregnancy.

Ectopic Pregnancy

While IUDs reduce the overall risk of any pregnancy, if a pregnancy does occur, it is more likely to be ectopic [1.6.3]. An ectopic pregnancy happens when a fertilized egg implants outside the uterus, most often in a fallopian tube [1.6.3]. This is a life-threatening medical emergency. About 50% of pregnancies that occur with a hormonal IUD are ectopic [1.6.4]. Symptoms include sharp abdominal or pelvic pain (often on one side), vaginal bleeding, dizziness, and shoulder pain [1.4.4].

Other Pregnancy Complications

If the pregnancy is intrauterine (inside the uterus), leaving the coil in place increases the risk of several complications [1.5.3, 1.9.3]:

Miscarriage (Spontaneous Abortion): The risk of miscarriage is significantly higher, with some studies showing rates of 48-77% if the IUD is left in [1.9.3]. Removing the IUD early in pregnancy can reduce this risk [1.5.3].
Preterm Delivery: The chances of delivering the baby prematurely are higher, even if the IUD is removed [1.9.2, 1.9.3].
Infection: There is an increased risk of infections like chorioamnionitis (infection of the amniotic sac and fluid) [1.9.3].
Placental Abruption: This is a serious condition where the placenta separates from the uterine wall before birth [1.9.3].

What to Do If You Suspect Pregnancy with a Coil

If you have an IUD and think you might be pregnant, it's crucial to act quickly.

Take a Pregnancy Test: A home pregnancy test can confirm if you are pregnant.
Contact Your Doctor Immediately: Whether the test is positive or you have symptoms like a missed period, severe cramping, or unusual bleeding, see a healthcare provider right away [1.4.3].
Confirm Pregnancy Location: Your doctor will perform an ultrasound to determine if the pregnancy is in the uterus or if it is ectopic [1.5.3]. This step is critical to rule out a life-threatening ectopic pregnancy.
Discuss IUD Removal: If the pregnancy is in the uterus and you wish to continue it, your doctor will likely recommend removing the IUD if the strings are visible [1.5.3, 1.5.1]. Removing it lowers the risk of complications like miscarriage and infection [1.9.3]. If the strings aren't visible, removal may be more complex [1.5.1].

Conclusion

Intrauterine devices are an exceptionally reliable form of birth control, but no method is 100% foolproof. While pregnancy with a coil is very rare, it is not impossible and carries serious health risks, most notably a higher chance of ectopic pregnancy. Understanding the signs of IUD failure and the symptoms of pregnancy is essential. If you ever suspect your IUD has moved or that you might be pregnant, seek immediate medical advice to ensure your health and safety.

For more information on contraceptive effectiveness, you can visit Planned Parenthood.

Frequently Asked Questions

The signs are the same as a normal pregnancy: a missed period, nausea, fatigue, and breast tenderness. However, since IUDs can cause irregular bleeding and cramping, it can be hard to tell the difference. If you suspect you are pregnant, take a test and see a doctor immediately [1.4.2, 1.4.4].

Both are more than 99% effective. However, studies show hormonal IUDs have a slightly lower failure rate (around 0.2%) compared to the copper IUD (around 0.8%) [1.9.3].

You should see a doctor immediately. They will first rule out an ectopic pregnancy. If the pregnancy is in the uterus, they will likely recommend removing the IUD to decrease risks of miscarriage and preterm labor [1.5.3].

You may experience new or worsening cramping, changes in your menstrual bleeding, or be able to feel the plastic tip of the IUD [1.8.2]. You can also check for the strings; if they feel longer or shorter than usual, or you can't feel them, see your doctor [1.8.1].

An IUD does not cause ectopic pregnancies, but because it is so effective at preventing pregnancy in the uterus, any rare pregnancy that does occur has a higher chance of being ectopic [1.6.3]. Overall, using an IUD lowers your risk of both uterine and ectopic pregnancy compared to using no contraception.

Yes, your fertility can return to normal very quickly after an IUD is removed. If you have the IUD removed but do not want to become pregnant, you should start using another form of birth control immediately.

No, an IUD prevents pregnancy; it does not cause an abortion [1.11.2]. It primarily works by stopping sperm from fertilizing an egg. A copper IUD can also prevent a fertilized egg from implanting [1.11.3].