Yes, an IUD can move, but true displacement is uncommon: large studies put the risk of partial or complete expulsion at roughly 2-10% over years of use, with most shifts happening in the first 3-6 months after insertion. A moved IUD usually sits lower in the uterus or rotates slightly; it rarely perforates the uterine wall (about 0.1-0.2% of insertions). Most people never feel a shift, which is why string checks and knowing the warning signs matter more than fear of movement.
What "Moving" Actually Means Inside the Uterus
An intrauterine device is a small T-shaped plastic frame, about 1.2 to 1.4 inches wide at the arms, placed at the fundus, the top of the uterus. It does not float freely. The uterine muscle contracts around it, and those contractions, plus the device's position relative to the endometrial cavity, determine whether it stays put.
Movement happens in three distinct ways. First, the device can descend toward the cervix, a partial expulsion. Second, it can rotate so one arm points down the cervical canal. Third, in the rarest case, it can perforate the myometrium, the muscular wall, and enter the abdominal cavity. Each has a different mechanism and a different level of urgency.
The key mechanism is uterine contractility. The uterus is not a static pouch; it contracts subtly throughout the menstrual cycle, more strongly during menstruation. A device that sits high and aligns with the cavity is stabilized by the muscle. One inserted too low, or in a uterus with an anatomical quirk, has less purchase and drifts.
How Often Displacement Happens: The Numbers
Expulsion rates vary by device and by study design, which is why headlines range so widely. Pooled data from large cohorts place complete expulsion at about 3-5% over 5 years for copper IUDs and roughly 2-4% for hormonal IUDs. Partial expulsion, where the device is lower but still partly in the cavity, is less consistently counted and may add another 2-5%.
Timing concentrates the risk. Roughly half of all expulsions occur within the first 3 months, and the majority within the first year. After the first year, the annual risk drops to well under 1% per year. This is why follow-up matters: the uterus is most reactive right after insertion.
Perforation is a separate, rarer event. Reviews estimate it at 1 to 2 per 1,000 insertions, with higher rates during breastfeeding, in the first 6 months postpartum, and when the uterus is retroverted. Perforation is not the same as movement; it is a placement injury that may only become apparent later.
In plain terms: most IUDs stay where they are put, a small minority slip down or rotate, and a tiny fraction go through the wall.
The Timeline: When and How Shifts Show Up
| Time after insertion | What is happening | Typical risk level |
|---|---|---|
| Day 0-7 | Uterus contracts around the new device; cramping peaks | Highest single-week risk of low placement |
| Week 2-6 | First follow-up string check; early partial expulsions surface | Elevated |
| Month 3 | Most early expulsions have occurred; position stabilizes | Moderate |
| Month 6-12 | Risk falls sharply; strings should feel consistent | Low |
| Year 1-3 | Device sits in steady state; annual risk under 1% | Very low |
| Year 3-5 | Hormonal devices near replacement; position usually stable | Very low |
| Any time | Perforation or migration can rarely present late | Rare |
The pattern is consistent across device types: risk is front-loaded. A device that has survived 12 months without shifting is statistically unlikely to move later, though "unlikely" is not "never."
What Makes an IUD More Likely to Shift
Several factors raise the odds, and they interact. Insertion by a less experienced clinician is one of the strongest modifiable predictors; proper placement at the fundus reduces later descent. A device placed too low at insertion is more likely to be expelled.
Uterine anatomy matters. A retroverted or sharply anteverted uterus, a septate uterus, or fibroids that distort the cavity can all reduce the device's stable seating. Postpartum insertion, especially within 6 months and during breastfeeding, raises both expulsion and perforation risk because the uterine wall is softer and the cavity is still involuting.
Age and parity play a role: younger users and those who have never been pregnant have slightly higher expulsion rates. Heavy menstrual bleeding also correlates with more contractility and a modestly higher risk. None of these factors makes movement likely; they shift a small number into a slightly larger small number.
Signs an IUD Has Moved and What to Check
Most shifts are silent. When symptoms appear, they tend to be one of a small set. The most reliable self-check is feeling the strings: they should be reachable at the cervix and roughly the same length as before. Strings that suddenly feel longer, shorter, or missing suggest the device has moved up or down.
A bulging device at the cervix, or feeling the plastic itself, is a red flag for partial expulsion. New or worsening cramping, pain during sex, or a partner feeling the device during intercourse can also signal a low position. A missed period or a positive pregnancy test with an IUD in place warrants immediate evaluation, because a displaced IUD raises ectopic pregnancy risk.
Warning signs that require same-day care:
- Feeling the hard plastic of the device at the cervix or in the vagina
- Strings that cannot be found after previously being palpable
- Severe or one-sided pelvic pain, especially with fainting
- Heavy bleeding with dizziness
- A positive pregnancy test while using an IUD
- Fever with pelvic pain or unusual discharge
Correcting a Common Misconception: The IUD Does Not "Get Lost"
A frequent fear is that the device wanders into the body. In reality, the IUD cannot travel through the uterus on its own; it either stays in the cavity, descends into the cervix, or, in the rare perforation case, passes through the wall at insertion or shortly after. Once in the abdominal cavity it does not migrate into organs.
A second misconception is that a shifted IUD always fails. A device that has rotated but remains in the cavity often continues to work. Copper IUDs retain most of their contraceptive effect if still intrauterine; hormonal devices may deliver slightly less reliably if partially expelled. The distinction between "moved but functional" and "expelled and non-functional" matters, and only imaging or a clinician's exam can tell them apart.
A third is that cramping means the IUD moved. Cramping is common in the first weeks and around periods and does not by itself indicate displacement. Symptoms alone are a weak signal; string checks and ultrasound are the real tests.
Checking, Confirming, and What to Actually Do
The practical protocol is simple and low-cost. Check your strings after each period for the first year, then periodically. Use a clean finger, feel the cervix, and confirm the strings are present and consistent. If something feels different, do not panic; book an evaluation.
Confirmation is straightforward. A pelvic exam can often detect a device at the cervix. Ultrasound is the definitive test for intrauterine position. If the device is missing from the uterus, an abdominal X-ray or CT locates it. Removal of a displaced device is usually a quick office procedure; a perforated device may require a minor surgical retrieval.
Per the CDC's 2024 U.S. Selected Practice Recommendations for Contraceptive Use, a single follow-up visit after insertion is reasonable, and routine repeat checks are not mandatory for everyone, which is why self-monitoring fills the gap. If you switch devices or reinsert after expulsion, the front-loaded risk clock resets.
Concrete actions:
- Note your insertion date and schedule a string check at 4-6 weeks.
- Learn what your strings feel like at baseline so changes are detectable.
- Use backup contraception for 7 days after any reinsertion.
- Report a positive pregnancy test immediately, not at the next visit.
- Keep your device's brand and model on hand for any evaluation.
- Do not attempt to pull or reposition the device yourself.
Limits of the Evidence and What Remains Uncertain
The numbers here are ranges, not certainties. Expulsion rates differ across studies because definitions differ: some count only complete expulsion, others include partial descent and rotation. Follow-up duration varies, and many cohorts rely on self-report. That is why a single figure like "5%" should be read as an order of magnitude, not a precise personal risk.
Perforation data come largely from large registry reviews and may undercount asymptomatic cases. The relationship between heavy bleeding and expulsion is observed but not fully explained mechanistically. And long-term outcomes for repositioned versus replaced devices are not well studied; clinical practice varies on whether a rotated but intrauterine device should be left in place or exchanged.
What is well established: movement is possible, it is most likely early, it is usually detectable through strings or symptoms, and it is rarely dangerous when addressed promptly. The IUD is one of the most effective reversible contraceptives precisely because most of them do not move, and the ones that do are usually caught before they fail.