ANTIFERTILITY EFFECTS OF HERBAL PLANTS CONTRAINDICATED DURING THE FIRST TRIMESTER OF PREGNANCY IN SIDDHA MEDICINE – A REVIEW

Siddha medicine advises against the use of a number of medicinal plants during the first trimester of pregnancy. Many of these plants have also been examined in laboratory studies for effects on fertility, the oestrous cycle, implantation, ovarian function and uterine contractility. These effects offer a plausible pharmacological basis for the traditional caution, because the first trimester is the period in which fertilisation products implant, the corpus luteum and progesterone support are critical, and organogenesis takes place. This narrative review aimed to summarise the antifertility and related reproductive effects reported for 24 herbal plants contraindicated during the first trimester in Siddha medicine, to identify the pharmacological patterns that recur across them, and to discuss the implications for traditional practice and for herbal safety in early pregnancy. A compiled evidence table of 24 plants, with plant parts, phytochemistry, pharmacological activity and a source reference for each entry, was read in full. Reproductive and antifertility information was extracted, grouped by type of effect and graded by the kind of evidence available, and summarised qualitatively. This is a narrative review; no systematic search, pooling of data or formal quality appraisal was undertaken. Experimental antifertility or pregnancy-interrupting data were reported for eight plants (Plumbago indica, Aloe barbadensis, Aristolochia bracteolata, Nigella sativa, Gossypium herbaceum, Ferula asafoetida, Gloriosa superba and Coriandrum sativum). Hormonal, oestrous-cycle or uterine-function data were reported for three further plants (Sesamum indicum, Anethum graveolens and Cissus quadrangularis). Four plants had only statement-level or indirect reproductive information, and nine plants had no reproductive data in the source material. The reported effects were anti-implantation activity, reduced conception, ovulation inhibition, depletion of antral follicles and corpora lutea, uterine atrophy, altered oestrogen and progesterone concentrations, increased uterine contractility and abortifacient action. Experimental evidence supports a pharmacological basis for the Siddha first-trimester contraindication of several of these plants, mainly through effects on implantation, ovarian function, hormone balance and uterine contractility. Almost all of the evidence comes from animal studies using crude extracts at doses that cannot be translated directly to human use. Concentrated preparations of these plants should be avoided in early pregnancy until their reproductive safety has been properly evaluated.