Originally Posted by anjrew531
If you have sex with a girl and a week after she has her period is it definate she is not pregnant
If I read the post correctly, I think he's asking that if the girl has her period a week after the encounter, could she still be pregnant.
If that's the question, then I'd say most likely she's not. Not definite, because it IS possible to have your period while pregnant, but the timing would indicate she most likely isn't.
As for being absolutely sure, if no baby pops out in 9 months, then you're clear.