My situation was a little different but DH had an accident during a time when we weren't ttc. I realized it was around O time and we weren't using any protection so I went out to get the morning after pill. I took it and then followed my ovulation by opks. I had a 5 day surge because the MAP was trying to delay my ovulation. Well, I still ended up getting pregnant anyway however I ended up losing that baby, we think from the effects of the MAP (it not only delays ovulation but also thins your uterine lining and the doctor didn't think it was thick enough for the egg to implant properly). So to answer your question simply: yes it can happen. Good luck to you!