red raspberry tea safe? (not raspberry leaf)

Nicole
 I had my first check up today at 8w1d and I mentioned nausea to my Dr. and he recommends brewing red raspberry tea with fresh ginger. Pretty sure he did not say 'raspberry leaf' even though I know that is good for later in pregnancy. Basically he wants me to stay hydrated as much as possible without consuming sodas etc. 
My question is, which herbal teas are safest to consume during first trimester? He didn't seem alarmed about any herbal teas in general as long as they are caffeine free. I'm wondering what all these herbal tea phobias are about that I'm reading around the web and what exactly do you ladies drink each trimester during pregnancy?