It can be pg related - a lot of women have what can be descirbed as a metallic taste, like blood or copper/brass taste...I had it also.
But I also got very bad gingivitus (sp?) whilst pg too, so often it WAS actually blood! lol even just a little can taste horrid.
If the gum gets rid of it, ace! Just keep in mind that most chewing gum can have laxative effect with prolonged use