I prefer pickled sushi ginger which is easier to digest and less heating. And sea bands or a small magnet on the wrist can reduce the nausea altogether without herbs. You do have some hormonal protection against illness, although that is not absolute. Echinacea is generally recognized as safe, but reserve it for real need. Curly or yellow dock tincture can help you assimilate the iron in your foods without binding you up like the iron in prenatal vitamins.
Some authorities think it has too strong a downward action.
And it is probably good to err on the side of caution and to avoid it in the first trimester. I know many people who have used it throughout, but I'd rather be cautious. You do want to take sources of folic acid however, even if you avoid Prenatlins. I also suggest that all herbs be taken in a form that you can taste- tinctures, teas or fresh and that they be avoided if you feel distaste. I developed a strong aversion to coffee, alcohol and vitamin supplements before I realized I was pregnant.