chamomile is alright. Stay away from the rose petals and licorice roots and lemon grass an citrus herbs just in case.
And ask your dr about it.
It depends. If you search for it online you'll find different answers. Some of them are abortive, others will make you get contractions, others have a lot of caffeine, and others will lower the folic acid in your body. And of course there are some that are alright as long as they are not consumed all the time. Ask your doc for some opinions ;-)
ps: I drink chamomile and jazmin tea once in a while, i love them