believe me I have unfortunately become an expert of yeast infections just recently!!

I have had a reoccuring one that wont go away with this pregnancy!!
symptoms can include feeling a constant itching or burning sensation down below and a white clumpy discharge. The longer you have it the worse the irritation becomes!
I have been treated for thrush 4 times in this pregnancy and never once been given the oral pill because I was told not to take it either. I have had creams and pessarys (sp?) Which are definitely safe to use. Although I cant see why your doctor would give it to you if it wasnt safe
Best things you can do to avoid them are what vanessa said above, and use unperfumed products in your bath like soap, bubble bath etc, and make sure your drinking enough fluids, always use panty liners too esp, while pregnant! It might be an idea for your partner to be treated too, this is just done with the same cream that you could use. It can be passed backwards and forwards between you both really easily through intercourse and he may have no symptoms at all