Many herbs contain steroids that can affect the baby's development during pregnancy and/or nursing. Some may be of a mild toxic type, and some may be strong uterine stimulants. Please read this section carefully and take heed.

Angelica - stimulates suppressed menstruation

Black Cohosh - uterine stimulant - mostly used during labor

Blue Cohosh - a stronger uterine stimulant

Borage oil - a uterine stimulant - use only during the last few days of pregnancy

Comfrey - can cause liver problems in mother and fetus - use only briefly, externally only, for treating sprains and strains

Elder - do not use during pregnancy or lactation

Fenugreek - uterine relaxant

Henbane - highly toxic

Horsetail - too high in silica for the developing fetus

Licorice Root - can create water retention and/or elevated blood pressure

Motherwort - stimulates suppressed menstruation

Mugwort - can be a uterine stimulant

Nutmeg - can cause miscarriage in large doses

Pennyroyal Leaf - stimulates uterine contractions (NOTE: Pennyroyal essential oil should not be used by pregnant women at any time!) - do not handle if pregnant or nursing

Rue - strong expellant

Saffron - can cause miscarriage and other problems

Shepherd's Purse - used only for hemmorhaging during/after childbirth

Uva Ursi - removes too much blood sugar during pregnancy and nursing

Yarrow - uterine stimulant

(From China.com)