Getting pregnant while using Nexplanon is extremely rare. The implant has a Pearl Index of 0.02, meaning roughly 2 out of every 10,000 users become pregnant per year during use. That makes it the most effective reversible contraceptive available. But pregnancies do happen, and there are specific reasons why. If you’re asking because you want to become pregnant, the answer is simpler: have the implant removed, and fertility can return almost immediately.
Why Nexplanon Almost Never Fails
The implant works by steadily releasing a synthetic hormone into your bloodstream. This hormone does three things at once: it stops your ovaries from releasing eggs, thickens the mucus at the entrance to your uterus so sperm can’t get through, and thins the uterine lining so a fertilized egg would have difficulty implanting. With all three mechanisms working simultaneously, the margin for failure is vanishingly small.
A large post-market study (the NORA study) tracked thousands of users and found a Pearl Index of 0.04 when including pregnancies that occurred within seven days of removal. Under perfect conditions, the rate drops to essentially zero. The FDA recently extended the approved duration from three years to five, based on a clinical trial of 399 women that recorded zero pregnancies during years four and five of use. That trial included a wide range of body sizes, with 38% of participants having a BMI of 30 or above.
What Actually Causes Implant Pregnancies
When pregnancies do occur with the implant, they almost always trace back to a specific, identifiable cause rather than the device simply “not working.”
The most common reason, by a wide margin, is failed insertion. A post-marketing review of 127 unintended pregnancy cases in Australia found that 84 of them involved an implant that was never actually placed in the arm. The insertion seemed to go normally, but the rod didn’t end up under the skin. This is why your provider should have you feel the implant in your arm immediately after placement, and why you should periodically check that you can still feel it.
Medications That Interfere
Certain drugs speed up how quickly your liver breaks down the hormone released by the implant, potentially dropping levels low enough for ovulation to resume. The FDA label specifically names these as risks:
- Seizure medications: carbamazepine, oxcarbazepine, phenytoin, felbamate, topiramate
- Antibiotics and antifungals: rifampin, griseofulvin
- Sedatives: barbiturates
- Herbal supplements: St. John’s wort
- Other: bosentan (used for pulmonary hypertension)
If you take any of these long-term, the FDA recommends using a different contraceptive method entirely, not just adding a backup. Short courses of these medications also warrant a conversation with your provider about additional protection.
Pregnancy Symptoms vs. Normal Side Effects
One of the most unsettling aspects of Nexplanon is that its common side effects overlap heavily with early pregnancy signs. The implant frequently causes missed periods (sometimes stopping them completely), breast tenderness, nausea, and mood changes. These are the same symptoms that typically prompt someone to take a pregnancy test.
If your periods were irregular or absent on the implant and that pattern suddenly changes, or if you develop new symptoms like extreme fatigue or frequent urination, a pregnancy test is a reasonable step. Home tests are reliable by the time you’d notice symptoms. The key thing to know: if you do become pregnant with the implant in place, there is a slightly elevated risk of ectopic pregnancy, where the embryo implants outside the uterus. Ectopic pregnancies can be dangerous and require prompt medical attention. Sharp pain on one side of your lower abdomen, dizziness, or unusual bleeding are warning signs.
If You Want to Get Pregnant
Nexplanon is fully reversible. A provider removes it through a small incision in your arm, typically in just a few minutes. Unlike some other hormonal methods, there’s no waiting period for fertility to bounce back. Ovulation can resume within days of removal, and pregnancy is possible right away.
There’s no medical need to “flush” the hormone from your system or wait a certain number of cycles before trying to conceive. If you’re planning a pregnancy, the practical step is simply scheduling a removal appointment. Some people conceive within the first cycle after removal, while others take a few months, which reflects normal variation in fertility rather than any lingering effect of the implant.
Checking That Your Implant Is Working
The single most important thing you can do is confirm the implant is physically in your arm. Press your fingertips over the insertion site on your inner upper arm. You should feel a small, firm rod about the size of a matchstick just beneath the skin. Do this periodically, especially in the first few weeks after insertion.
If you can’t feel it, don’t assume it’s still working. A missing or deeply placed implant may not release hormone effectively. Your provider can locate it with imaging and determine whether it needs to be replaced. Beyond that, keep a mental note of any new medications or supplements you start. If anything on the enzyme-inducer list above enters the picture, bring it up with whoever prescribed it and with whoever placed your implant.