Traditional medicinal plants have been considered a reliable resource for healing in local communities worldwide for thousands of years, and more than three-quarters of the world population trust traditional herbal medicine for health care. There is an increasing interest in traditional herbal remedies due to their safety, efficacy, cost-effectiveness, eco-friendliness, ready availability, cultural acceptability, and fewer side effects than synthetic drugs (
67). They are also the source of drug discovery and may even be considered the origin of modern medicine (
68).
According to the WHO report, women comprise a group with the most frequent use in complementary and alternative medicine therapy (
69). During pregnancy, especially in developing countries, women tend to self-medication with herbs as natural and safe substances. However, the lack of knowledge of side effects and the interactions of herbal medicines with chemical drugs may cause carcinogenic or toxic compounds in the body (
61).
This study tried to assemble the available evidence about the effect of medicinal plants on abortion in Persian and conventional medicine references (
12,
13), with different mechanisms including estrogenic activity, increased menstrual flow, induced abortion, uterine stimulation, increased bleeding risk, uterine contraction, uterotrophic activity, and stimulant action on uterine muscles (
70). Some medicinal plants with abortive effects introduced in Persian medicine can decrease progesterone levels, such as
M. chamomilla (
57,
65). Progesterone is a critical hormone in early pregnancy. A low serum progesterone level is associated with threatened miscarriage (
71).
Minimal human studies have been done, primarily in-vitro or in-vivo. Two clinical trials assessed the effects of medicinal plants (
S. indicum L. (Sesame) and
C. myrrha) on incomplete abortion management. Both studies showed that these plants are effective (
29,
33). A prospective case-control study found that the miscarriage rate was significantly higher among female farmers with Saffron exposure (
51).
The present study showed that some studied plants are emmenagogue (eg,
M. chamomilla,
Z. multiflora, and
S. lavandulifolia) or delivery facilitator (not abortifacient, eg,
C. sativus (Saffron)) (
12,
13). Many of these plants are present in the daily diet, including
Cicer arietinum L. (Hemmas, Nokhod),
Phaseolus vulgaris L. (lubya), rice bran (first or outer skin of rice),
Oryza sativa L. (oroz, Berenj),
L. albus,
Cinnamomum aromaticum Nees.,
Apium graveolens L.,
S. indicum L. (Konjed),
Daucus caruta L.,
Piper nigrum L.
Studies on the abortifacient activity of some plants, such as
C. sativus, revealed controversial results at different doses (
49). Our findings revealed that the abortifacient activity of
L. inermis L. (Henna),
J. sabina (Abel or Abhal), and
S. indicum L. (Konjed) had been proven in both traditional medicine and recent studies (
29,
57,
61).
Studies carried out on
P. harmala have shown that the consumption of this plant interrupts fetal growth, and it is an abortifacient plant (
43). In Persian medicine,
P. harmala is also used as feticide (
12,
13).
Crocus sativus agents share common effects on cell division and DNA cycles, leading to abortion. The impact of
C. sativus on abortion is more approved, while in Persian traditional medicine, it is used as a placenta extractor and a delivery facilitator (
12,
13). Also,
R. graveolens L. has no abortion induction effect (
47), while in Persian medicine texts, it is also known as an abortifacient to menstruation and emmenagogue (
12-
14).
Based on traditional medicine contexts, even though pineapple does not affect pregnancy, embryos, and abortion, recent studies have proven these effects (
72). Anchusa italic has an abortive effect, while there is nothing mentioned in Persian medicine contexts in this regard (
73). Some of the plants studied in new medicine are not effective or have poor effects, which can be related to factors such as part of the plant used (leaf, root, etc.), preparation method (aqueous, water extract, alcoholic, etc.), or medication rout of use (oral, topical, suppository, or water).
The present study results can be used as an outline for future studies about effective plants in conventional and complementary medicine. Further studies are needed to understand better the effects of medicinal plants on incomplete abortion management. Further pharmacological and clinical studies are recommended to evaluate the efficacy of all Persian medicine plants in abortion and their possible action mechanisms. Plants such as
Citrus medica cedrata, Mentha longifolia L.,
Achillea millefolium,
Carum petroselinum,
Narcissus tazzeta L.,
Hypericum perforatum L.,
Cheiranthus cheiri L.,
Arum italicum L.,
Rubia tinctorum L.,
Ferula gummosa Boiss,
Nigella sativa L. (Shoniz), and
L. albus have three or four effects and high potency and frequency in Persian medicine (
12,
13). Therefore, using these herbs in future clinical studies is proposed for incomplete abortion management.
4.1. Conclusions
The abortifacient activity of L. inermis L. (Henna), O. chironium L. (Jooshir), P. rosea (Stumbag, Shitraj), and J. sabina (Abel or Abhal) have been proven in both traditional medicine and recent studies. The properties of many traditional plants with abortifacient activity are unknown in modern medicine; however, they should not be used in pregnant women. However, it may have the power to be entered into modern medicine. Identifying the pharmacology and their action mechanisms may be helpful to introduce them as a potential alternative for chemical agents in the management of induced or incomplete abortion with possibly lower side effects.