Herbal tea helps to cure skin conditions, hypertension, insomnia and many more. Drinking peppermint herb tea before bed can also lead to benefits for your stomach. I am using it for some years and its wonderful.
Raspberry leaf tea has been used for centuries to strengthen the uterus and as a tonic for women, including pregnant women, but probably shouldn't be used until after three months. On the other hand, you don't have to use it -- people do have babies without it. What the claim is that in the latter stages of pregnancy by tonifying the uterus it reduces the chances of a difficult labor, and also promotes the production of breast milk. Discuss it with a midwife or someone expert in such things and then decide what you want to do. As for the herbs mentioned above, I'm not sure all of them are bad during pregnancy, or even most of them. But since most of what we know is often theoretical, it's hard to know for certain. Best to be careful when you're pregnant and check with a professional who knows herbs. Of course, you obviously wouldn't want to use mistletoe, as it's somewhat toxic, and ephedra is speed, and pennyroyal is an abortifacient. Those are pretty obvious.
P.S. don't drink anise, catnip, chamomile, comfrey, ephedra (called ma huang in traditional Chinese medicine), European mistletoe, hibiscus, horehound, Labrador, lemongrass, licorice root, mugwort, pennyroyal, raspberry leaf, rosemary, sage, sassafras, stinging nettle leaf, vetiver, and yarrow when you are pregnant.
Its effectiveness hasn't been proven. In any case, it should be used only near term and under the supervision of a healthcare professional. If you were my wife I would say NO!
But that's my opinion