Yes, the freeze-dried nettle caps work well for some folks. You might have to try different things. Goldenrod leaf tea/infusion works well. Eyebright. No ephedra.
There are some Chinese patent formulas that work well but check with a TCM practitioner about use in pregnancy.
Homeopathy works well too- consult a homeopath for help getting the proper remedy
I would not use any of the more "medicinal" herbs all the time- just when you need them. Nutritional herbs are more like food. You can build your system up taking these on a regular basis. Nettle leaf, oats, alfalfa, red clover, red raspberry can all be alternated throughtout pregnancy (or life!)