If I got my "period" 3 days after sex, does that mean I'm not pregnant? I know the sperm has to fertilize an egg and then release a hormone that stops your period, but is 3 days enough to stop your period? The period was pretty normal, lasting 5 days. It was heavy when it first started, with some small clots. The blood was dark red and I had cramps. I also had sex early last month around April 14th. Oh I forgot to mention the first time I had sex I was on the pill, but had missed 2 and didn't use a condom but used withdrawal. The second time which was about 3 weeks later I was on the pill and hadn't missed one. He did ejaculate inside me. I also have no pregnancy symptoms. So is getting a period 3 days after sex mean I'm not pregnant? Or can the bleeding be some kind of vaginal bleeding due to pregnancy?