Due to the way human reproduction works, one can not menstruate when one is pregnant.
However, in the first few months of pregnancy, it is quite normal to experience spotting and slight bleeding (for example when implantation happens, several days after conception), which some women mistake for mentstruation.
If you are worried about pregnancy even though you have menstruated as usual, I'd recommend that you take a pregnancy test to clear your mind.
Also, just in case you were worried about being pregnant because you had unprotected sex, please don't forget that even though you most likely didn't get pregnant (because you menstruated), you still had an STD risk, and need a screen.
Spike: (In response to being asked to fight a troll) "I would, but I'm paralyzed with not caring very much."
[This message has been edited by Alaska (edited 02-05-2003).]