I have heard of people still having periods whilst preg. but when i think of the a&p side they aren't relaly periods...
I use to work with a woman who was sick as a dog for 7 months, saw specilists and doctors and no one could work out what was wrong with her, until some smart person gave her a pg test. she took one right at the start and was neg so didnt think anymore of it. but turns out she was preg...and yea didnt know til 7 1/2 months in