When researchers analyzed the data from the National Birth Defects Prevention Study, they realized that about 10 percent of women used herbs during pregnancy. The most frequently used herbs were ginger, ephedra and chamomile, which may help with some common pregnancy symptoms, such as nausea, fatigue and insomnia, respectively.
"Herbs can help treat some pregnancy discomforts so that you don't have to resort to medications," says Julie McKee, MD, professor of medicine at the University of Texas Medical Branch in Galveston. But because herbs have the potential to harm as well as to heal, it's important to know which herbs you should avoid during pregnancy and when you're trying to conceive. It's also essential to talk with your healthcare provider about any herbs or supplements you've been taking and to check with her before taking any new herbal treatments.
Even though ephedra was one of the herbs most commonly used by pregnant women, it's not a good idea for pregnant women to take it. Ephedra increases the risk of heart problems and stroke—no small risk when your cardiovascular system is working overtime to supply you and your developing baby with the oxygen you need.
St. John's Wort
Pregnant and breastfeeding women should avoid taking St. John's wort, an herb commonly used to treat depression, said researchers presenting in 2009 at the 21st Annual Meeting of the American Association of Naturopathic Physicians. Not only does St. John's wort have the potential to interact with some medications commonly prescribed during pregnancy, it also has the potential to contribute to lower birth weight. Nursing babies may become drowsy or lethargic, or exhibit signs of colic, if their mothers take St. John's wort.
Pennyroyal has historically been used to treat a variety of ailments, ranging from stomach pain to breathing problems, but this herb is unsafe for most people and especially for pregnant women, according to the National Institutes of Health. Taking pennyroyal during pregnancy—whether you ingest it or apply it to your skin—can cause the uterus to contract and cause the start of menstruation, both of which can cause premature labor or miscarriage.
The gamma-linolenic acid in borage oil can help promote healthy skin, hair and bones and may have benefits for some health conditions, including rheumatoid arthritis and high blood pressure. But borage oil may harm developing babies and even cause early labor, so pregnant women should avoid using it.
This herb is mainly used by men, but pregnant women should be careful to avoid it. That's because it interferes with your body's hormone production, which can have dangerous effects during pregnancy and on the developing fetus.
Because cohosh stimulates the uterus and can cause problems with your baby's developing cardiovascular system, steer clear of both blue and black cohosh during pregnancy. These herbs are often used for menstrual and arthritis pain, so check your ingredient labels carefully if you take herbal remedies or supplements for these conditions.
Other Herbs to Avoid
Some herbs aren't clearly dangerous during pregnancy, but because they aren't clearly safe either, it's wise to err on the side of caution and avoid them. These herbs include chasteberry, red yeast rice, juniper berries, red clover and parsley. If you're not sure about the safety of an herb for your pregnancy, always check with your healthcare provider.