Maternal Dental

Hey guys!  So here I am with another question.  I just heard the weirdest thing.  I had no idea about this but apparently your oral health gets all crazy when you are pregnant.  I was reading about root canals and teeth falling out and lots and lots of gingivitis going on.  I guess it has something to do with pregnancy hormones but it does not make mouth happy.  Is this for real?  Did you notice any changes with your teeth and gums and such while pregnant?  I know dental hygiene is always important but is pregnancy a time to be militant about it?  Also I heard that you should not get any dental work done while pregnant, fillings and stuff.  But that you should get your 6 month cleaning religiously or you'll regret it.  What do you think?