What are the chances of getting pregnant?

Samantha
Ok! So I just started my period and I had some spotting going on last night. My hormones had me in the mood so my fiance and I had sex. Things were getting hot and heavy and we were in the moment when I told him I wanted him to cum inside of me. He is worried that im gonna get pregnant and I think the chances are very slim with me bleeding and being on my cycle.