I don't know how it is calculated or if it is random, but I just want to know the chances of my gf being pregnant. We were getting pretty frisky the other night and I went part way in, no condom, no ejaculation. We're talking about half-way in, I had pre-cum, her period hasn't rolled around yet (it's getting close) but I'm just wondering what are the chances of her being pregnant if anyone knows.