Your chances are pretty slim, so try not to stress yourself out...
i too completely agree with clysta and mrspincince052519.. though chances are comparatively very low but the possibility cannot be denied..
I agree. While it's not likely, sperm can mix with the natural fluids a female secretes and therefor swim up into the vagina. Sperm can on average survive up to 20 minutes exposed to air, but if it's warm and moist it can be much, much longer. Wait two-four weeks since your last sexual encounter and take a pregnancy test with first morning urine.
Hi:-) I'm going to assume that you mean your boyfriend pre-ejaculated outside of your Vagina because the female uterus is inside you. Pre-ejaculate can get you pregnant but being that he wasn't inside you, your chances of being pregnant are slim. Only because if it were outside sperm doesn't live that long. If he penetrated and pre-ejaculated inside you then you may have a reason to think you could be pregnant. In any event with what you've described I highly doubt you're pregnant. If you worry about getting pregnant I would strongly recommend using condoms as well as a form of birth control for you. Better safe than sorry:-)