I am a 20 year old male. She, an 18 year old female. Once she tricked me into impregnating her, she left, and found herself another. If she continues to have unprotect sex with this partner allowing him to also *** inside of her, will this change anything?

"Tricked you"? How was that? Nothing will change, you are the father of the child, your DNA is part of that child and nothing afterward will change that fact.

No. She gets pregnant by whomever's sperm gets there first.

Maybe you get lucky and it's not yours, so next time you use the big head rather than the little head to do the thinking for you.

Usually, if some woman I barely know comes up and wants to have uprotected sex, the first thing I think of is what is she trying to give me, or trap me into.

And even if I do know her, I wear a condom. You don't know where that thing has been.

You're still the father. The only thing I would be worried about is the possibility that she may catch an STD while pregnant. Some STD's won't affect the baby but others can.

You've said you had sex with this girl once, then she left,found herself another man.

How do you know that she is pregnant at all!! Are you thinking that because you had unprotected sex once, then she must be pregnant... not necessarily.

Was the pregnancy confirmed before she left? It couldn't have been as you say you only did it once then off she went with another guy.

If I were you I'd be asking for a DNA test, before admitting to being the father, of a child from this girl.

If of course she is indeed pregnant!!

The other man's sperm will not effect the unborn child. As was said, it would be wise to obtain a DNA test right after the baby is born to determine if the baby is indeed yours.

First are you really 20,

But when the child is born ask for a DNA test to prove who the father is. Does not matter how many people she has sex with, only one gets her pregnant, any after that does not change anything