Allright well here's my question which is pretty confusing. My boyfriend and I had been trying to get pregnant. After my last period (which was from around August 25th to August 30th) that was the last time we basically tried before we had a break up. I believe the last time that he ejaculated in me was around the 4th of September. The thing is that shortly after we broke up I slept with another guy on the 10th of September and there could be chances that it's his as well. Now my question is... I'm going for an ultrasound on the 8th and considering the fact that a baby starts his/her first heartbeat 5 weeks into pregnancy could it mean that if the baby has a heartbeat when I go for the ultrasound that it's my boyfriend's?