If you ejaculate inside the vagina, but take plan b about an hour later, what are you chances of pregnancy?

Possible: Anytime you have unprotected sex, there is a possibility of pregnancy. People are not as predictable as we might like and both sperm and egg have been known to be viable longer than expected. Always use condoms for std protection and another effective birth control method when you have sex, if being a parent is not something you want at this time!

Plan B: I think the current thinking is that Plan B is about 50% effective. Perhaps using birth control or contraception before sex rather than after sex would be much more wise in the future.