Can Nexplanon interfere with pregnancy test results? Some of mine have been faint positives, but ones done by others have supposedly been negative (I didn't see those ones, so I'm just going based on what they said). I've had the implant in since the end of May and would have gotten pregnant either the end of May or middle of June. I was told to use backup protection for two weeks, but now I'm hearing I probably should have used backup protection for the first month after getting it put in. I would go get a blood test, but my insurance was cut off and I have to try to get it back.