Although herbs are natural, not all herbs are safe to take during pregnancy. Herbs may contain substances that can cause miscarriage, premature birth, uterine contractions, or injury to the fetus. A pregnant woman should avoid goldenseal, pennyroyal, rue, blue cohosh, black cohosh, beth or birth root, and cramp bark to name a few. Before you buy herbs, research it to make sure it's safe to take. Please read "Pregnancy, Breastfeeding, and Detoxing".