The safe use of herbal medicines in pregnancy became a hot topic in the late 1960′s following the tragic Thalidomide scandal. The drug was initially marketed as a sleeping aid and safe for pregnant women, but before long an alarming correlation was drawn between the physical malformation of babies and the use of Thalidomide.
The drug was withdrawn from sale in Britain, a new drafting of the Medicines bill in 1964 also saw the introduction of a new ministry, set up to scientifically validate the safety and effectiveness of herbal remedies. The fiasco also led to a quick amendment of the American Food and Drug Act, giving them power to demand that drugs be proved not only effective, but also safe.
This was to apply not only to pharmaceutical drugs, but also to all herbal medicines. The very notion must have been far more of a nightmare to herbalists of the time, than the possibility of regulation is today. There was only one solution, to endevour upon the enormous task of trying to classify all possible herbs used by practitioners.
The British Herbal Pharmacopoeia is based on what the ministry guidelines listing safe and effective herbs as those which had “been in use for a long period without giving any ill-effect,…(and) a herb for which a monograph appeared in any standard reference book and was not poisonous”
Accordingly, herbs were categorised according to their constituents and those deemed unsafe, were thereby had their use restricted. However, this bought to light a new problem; not all herbs containing a constituent deemed toxic appeared to produce toxic effects. In this lies evidence of the “whole plant theory” held by herbalists, for it shows that not every constituent will act in the same way, depending on the other constituents within the same plant specimen. An example of this, is the general contraindication for Anthraquinones in pregnancy, however as Pengally notes, the constituent Hypericin from Hypericum perforatum (St Johns wort), “is a dehydrodianthrone, structurally an anthraquinone. However it does not break down to anthraquinone in the bowel and is without laxative action.”
Obviously, to test every constituent in every herb used by practitioners, would cost enormous research dollars, not to mention the insurmountable hours, days, weeks and years involved in such an undertaking. Thus we are faced with a problem whereby science declares that proof of an evidential nature must be gained in order to deem a herb safe, yet the possibility of correctly measuring this safety is beyond means.
Similarly there may be confusion when we look to herbal actions as a means of classification for safety, for often we find that an action may be changed with dose, in example, an aperient in large doses becomes a laxative, and thus cannot be deemed unsafe in pregnancy, but should be prescribed by a herbal practitioner who understands the range of safe dosage.
Thus we find that there is conflicting information between sources and no one ideal means by which to classify herbs as safe or unsafe for use in pregnancy. We can however, use the information science has to offer and combine this with the traditional understandings of a herb to give a more rounded view. To this end, we must not forget the traditions from which herbal medicine was born, particularly the midwives of history who so skilfully dispensed herbal medicines without the aid of science. It is these traditions and the folklore they incited which have provided the art of this modality, and will hopefully never be deemed by practitioners as less important than the science.
Constituents of Concern
There are certain constituents which have been deemed unsafe for use in pregnancy, however, in light of thewhole plant theory we must emphasise that the degree to which these herbs illicit their effects varies greatly not only between different species, but sometimes different plants of the same species.
Outlined below are just some of the constituents considered unsafe for pregnant women.
Thujone – Structurally a ketone. A neurotoxic convulsant and hallucinogen. Found in Thuja occidentalis, Artemisia spp and Salvia officinalis as well as Tanacetum vulgare and Salvia sclarea. Reputed in folklore for their abortifacient actions. Has emmenogogue properties and may also inhibit lactation, so is also contraindicated in breastfeeding.
Ascaridole – Structurally a terpene peroxide. Considered the most highly toxic of all essential oils.
Thymol – A monoterpene, has emmenogogue action and may irritate mucous membranes.
Eugenol – Structurally an Aldehyde
Apiole – A Phenolic ether (toxic when isolated)
Allyl isothiocyanate – A Sulphur compound
Abortifacient action. Found in Cystisus scoparius. Inhibit the function of glycoproteins, essential during pregnancy for endometrial glands & luminal epithelium to sustain cellular growth during pregnancy. This causes sloughing of the endometrial wall, resulting in an abortion.
Benzoin ??? – Contains cinnamic, benzoic & triterpene acids.
Kavain + Mehtysticin – From the Kava kava/Piper methysticum plant. Hypnotic and smooth muscle relaxant. Kava pyrones
Alstonine – Uterine stimulant
Alstonidine – Uterine stimulant
Resperpine – Steroidal Alkaloids
Found in unripe potatoes and tomatoes, these constituents have a teratogenic effect on the foetus.
Ephedrine – Found in Ephedra sinica. Restricted in Australia due to issues of safety and legal concerns
Caffeine – Found in Coffea arabica, Camellia sinensis, Cola nitida and Paullina cupana. A CNS stimulant that can pass the placental blood barrier to affect the foetus.
Sennosides A & B
Found in Rhamnus catharticus, Rhamnus frangula and Rheum palmatum, as well as Aloe barbadensis and Senna spp. Hypericin found in Hypericum perforatum also contains anthraquinone compounds but does not cause a laxative action.
Actions to be Aware of
The following is a list of some of the main actions which should be avoided by the untrained practitioner and should be either avoided or used with care by the herbalist. Abortifacients Bulking laxatives Emetics Laxative herbs in high doses Uterine stimulants Emmenagogues should not be given in doses of more than 1 gram per day.
Herbs have been categorised based on their actions into the following three groups
A. Herbs only to be used with caution in pregnancy
B. Herbs only to be used/not used in particular circumstances during pregnancy
C. Herbs that should never be used in pregnancy
Action Grading A B C
- Anthelmintic A
- Aperient A
- Bulking laxative B
- Uterine stimulant B & C
- Abortifacient C
- Emetic C
- Teratogenic C
- Emmenogogue B & C