Hi Polly, I had this problem when I was pregnant with my son, It only lasted for the 1st 12 weeks or so but it was truley revolting. I never found anything to mask it but I did find certain things made it worse. Milk and dairy products and eggs made mine worse. I also found that when I stopped taking my folic acid it cleared up as well. Hope this helps Hayley, Alexander 17 months and 35 week bump.