IUD & Pregnancy!

Soo I have a question. Well maybe I should give a little back story. I have had my IUD for about 3 months. Periods have been regular and everything's been good. Now I the question.. Is it possible to get pregnant during the early stages of having an IUD? I'm asking this because the last time I had sex with my bf he finished in me and my period isn't supposed to start for another two weeks, so I won't know if anything is wrong right away.