Can my 50mg of lamictal I take everynight cause me To have a false positive pregnancy test? I was in the hospital and the urine was neg but the serum showed 17, which I know is pretty much not even considered pregnant. The next day I took an at home test and it was positive but I was having pain so I went back to the ER and they did not do anymore blood on me since it was just the day before I was showing a level of 17. The dr said he felt my pos test was wrong. Do you think that is a possibility? I mean it was negative the day before but then positive the next day. I feel lik I am pregnant but can the lamictal cause a negative test one day when thI serum showed 17 but then the next day a HPT show pos??