See the DrugPatentWatch profile for mirena
What are the chances of getting pregnant while using Mirena?
Mirena is a levonorgestrel-releasing IUD. It is highly effective at preventing pregnancy, with typical-use pregnancy rates around 0.2% in the first year for people using it exactly as directed. That works out to about 1–2 pregnancies per 1,000 users per year.
How effective is Mirena by timeline (early vs later years)?
Effectiveness is highest when the IUD is correctly placed and stays in position. If it remains in place, Mirena continues to provide strong pregnancy prevention across subsequent years. If the device shifts, partially comes out, or is removed, pregnancy risk rises.
What most increases the chance of pregnancy with Mirena?
Pregnancy risk goes up when:
- The IUD is expelled (partially or fully).
- The IUD is not properly positioned.
- The strings are not followed up and placement has changed.
- The device has reached the end of its approved duration for pregnancy prevention (depending on the specific product labeling in your country).
If pregnancy happens with an IUD in place, clinicians typically assess urgently because pregnancy with an IUD has higher risks of complications (including ectopic pregnancy) than pregnancy without one.
How would I know if Mirena isn’t working?
Common warning signs that Mirena may have shifted include:
- New or worsening pelvic pain.
- Heavier or unusual bleeding.
- Feeling the plastic of the IUD, or having strings suddenly feel much longer/shorter than before.
- Losing the IUD (you may feel it coming out).
If you notice string changes or symptoms, get checked promptly with a clinician and avoid relying on Mirena until placement is confirmed.
What should I do if I think I might be pregnant?
Take a home pregnancy test if you have pregnancy symptoms or missed periods (though bleeding patterns can change with Mirena). If positive, contact your clinician right away. They will confirm the pregnancy and location and discuss next steps.