Definately. It is not good for your bladder nor your kidneys.
However it is a good idea to try and strengthen your pelvic floor muscles - to do so just use the same muscles you use when you are holding in your pee.
It is really bad for you...my doctor told me that it can cause some really nasty bladder infections (I actually got one from that) so if you need to go, go.
VERY! You can get a nasty bladder infection.
no its not I do it all the time