So I know that mommas and doctors are hot & cold when it comes to drinking herbal tea, because different herbs can have different side effects, etc etc.  So as a BIG tea drinker I not only cut back the amount of tea I drink (both black, herbal, and otherwise) and cut back the types of tea to just to black tea (my one 4-6oz cup a day), decaf black tea, peppermint tea, and rooibos/honeybush tea.   All of which are on the "safer" end of the tea spectrum - and I drank these (except the rooibos) all throughout my first pregnancy with no issues. And I don't drink all of these in a day, I'll drink a few cups throughout the week.