Potentially Dangerous Herbal Supplements in Pregnancy

Recently, I ran across an herbal tea marketed towards pregnant women in my local health food store. Curious, I did a quick glace at the ingredients expecting to see such innocuous ingredients as chamomile or maybe peppermint. What I saw was a laundry list of herbs that are either potentially dangerous or known to be harmful in pregnant women.

Thinking that this must be an isolated incident, I examined the list of ingredients in a variety of herbal teas and supplements marketed towards all stages of pregnancy. Four ingredients were common in nearly all of these products.

Firstly, the ingredient listing “nettle leaves” is remarkably uninformative as there are numerous species of the nettle family commonly used in herbal medicine. In addition there are several completely unrelated plants that share the common name of “nettle” but should not be ingested by human beings in any form. As stinging nettle is the most commonly used herb, I must assume that it is that plant to which they refer.

Stinging nettle is, among other things, a laxative. For those uncommon with home remedies, laxatives--including the old castor oil standby-- are the most commonly used methods of attempting to self-induce labor. There is a certain amount of both anecdotal evidence and medically based logic to these remedies; laxatives can cause uterine contractions. Obviously, this is not desirable in the first, second or early third trimesters.

In addition, stinging nettle is a diuretic. As such, it can lead to dehydration and Hypokalemia (excessive loss of potassium). The stress on the body from either of these conditions can potentially result in preterm labor.

Probably the safest ingredient in this particular tea and common in many similar products. The use of rose hip specifically for normal pregnancy health escapes me, however. Other than additional vitamin C and possibly very mild relief of some joint pain there is absolutely no benefit that I can see. Those women seeking the additional vitamin C can find it readily in food sources, such as fruit juice, that provide additional nutrition without the risk of unforeseen complications from herbal supplement use .

It should be noted that in pregnancies complicated by gestational diabetes, rose hips may be beneficial in controlling blood sugar levels. This is especially true in women who are attempting to control those levels with diet alone. In these circumstances, women may choose to discuss the option with their midwife or obstetrician. Conversely, women with anemia should probably avoid rose hips, as the herb may interfere with iron absorption.

There are several species of verbena and most are used in herbal remedies. Barring further identification, it can safely be assumed that this ingredient is common verbena, the plant that produces the herbal medication vervain. Once again, vervain has a history of use in pregnant women; midwives gave it to women in labor to intensify their contractions. It can also cause diarrhea and is still used today in many countries as a deworming medication for humans and livestock. Like stinging nettle, vervain is a diuretic.

The vebena plant has both sedative and relaxant properties that increase with each subsequent dosage. As such, infants born to mothers who have recently taken verain may be sluggish and have decreased respiration. In addition, while no specific studies have been published on the transference of vervain through breast milk, the herb was historically recommended to mothers of babies with colic. This provides at least anecdotal evidence that the herb may be passed on to an infant through nursing.

I am quite willing to admit that speaking against raspberry leaf use during pregnancy is not the prevailing opinion. The herb has been used by herbalists and midwives for centuries to ease childbirth and has a catalogue of anecdotal evidence proving its effectiveness for this purpose. As such, I am willing to concede that the herb is probably useful in the final weeks of the third trimester.

The main problem I have with most pregnancy teas containing red raspberry is that they are marketed to women in all stages of pregnancy.

The biggest risk involved with raspberry leaf is that it is believed to act in ways similar to estrogen in the blood system. Logically, pregnancy is not an appropriate time to be experimenting with any substance that alters hormone levels unless a very specific reason is present. In addition, the tannins contained in raspberry leaf can lead to kidney and liver damage if taken over an extended period of time or in large doses. As it is unclear how much, if any, of the chemicals are being passed through the placenta, I am concerned with the possible effects of any dose in the fetal blood stream during the formation of these organs.

On a completely subjective note, in addition to the above concerns-- which are rooted in mainstream medical science-- I have concerns about the number of anecdotal claims associating miscarriage with the use of raspberry leaf in early pregnancy.

In conclusion, to me the use of the herb in a healthy early pregnancy simply does not outweigh the risks.

This article was written for informational purposes. In no way should anyone rely wholly on its content to determine the safety or effectiveness of any herbal product. Women who are pregnant or nursing are STRONGLY advised to discuss the possible benefits and side effects of any herbal products with their midwife or obstetrician before taking it.

"TANNIC ACID: Uses, Side Effects, Interactions and Warnings" WebMD

"STINGING NETTLE: Uses, Side Effects, Interactions and Warnings" WebMD

"RED RASPBERRY: Uses, Side Effects, Interactions and Warnings" WebMD

"Verbena Effectiveness, How It Works, and Drug Interactions" emedicinehealth

"ROSE HIP: Uses, Side Effects, Interactions and Warnings" WebMD

Christine A. Larson Alternative Medicine: Health and Medical Issues Today Greenwood Publishing Group. 2007. Print

"Natural Herbs & Vitamins During Pregnancy" americanpregnancy.org