I've been reading reviews on my new medicine Lamitcal(LAMOTRIGINE) use to treat bi polar disorders. As I was reading I saw alot of people became preg while on birth control but the medicine Lamitcal makes it less effective. I'm using the arm inplant (Implanon) for my birthcontrol. Could I become preg while taking Lamitcal? My boyfriend hasnt been using a condom simply because the birthcontrol has been working for the past two years but now I'm scared that I can become preg.