Some organizations that specialize in herbs have done extensive testing on their safety. Often these organizations will list herbs with their safety ratings for the general population and also safety during pregnancy and lactation.
These ratings can be confusing, because there isn't a regulated rating system with herbs such as with categories of medicinal treatments. Therefore, it is best to consult with your health care provider or someone trained in using herbs before taking any natural medicine or herb during pregnancy.
While not all organizations agree on which herbs are safe or totally safe, the following herbs are unanimously considered unsafe during pregnancy:
Saw Palmetto – when used orally, Saw Palmetto has hormonal activity. According to EMEDTV, the herbal supplement works by blocking the conversion of testosterone into DHT (dihydrotestosterone), thereby decreasing the amount of DHT in the body. Since DHT is important for male genital development, if taken during pregnancy, theoretically, saw palmetto could cause abnormalities to the external genitals of a male fetus.
Goldenseal - potentially stimulates uterine contractions and crosses the placental barrier, according to Drugs.com.
Dong Quai – when used orally, due to uterine stimulant and relaxant effects. This herb is often used as a remedy for menstrual cramps, when used in a specific way. Midwives may use this as a way to stop early labor or help contractions, depending on the way it is used.
Ephedra - when used orally. Ephedra has several side effects that are contraindications for use during pregnancy, such as hypertension, increased metabolism, changes in heart rate and dizziness and nausea.
Black Cohosh – Midwives sometimes use black cohosh to help prepare or ripen the cervix for labor, possibly giving the impression that it is safe to use during pregnancy. However, the American Pregnancy Association warns that when you use the herb in early pregnancy, it might induce miscarriage.
Blue Cohosh – Holistic practitioners sometimes use blue cohosh to help treat ailments such as rheumatism, menstrual cramps and epilepsy. Midwives use blue cohosh to help stimulate uterine contractions and induce labor.
Roman Chamomile – In medicinal amounts, Roman chamomile can trigger contractions in the uterus, leading to an increased risk of miscarriage and preterm labor.
Pennyroyal – Can cause miscarriage and permanent damage to the uterus. Just a 5-g dose of pennyroyal oil can cause severe toxicity symptoms.
View the accompanying slideshow to see each herb in its plant state and to read more info.