Noura S Dosoky et al. Int J Mol Sci. 2021.
For a complete list of essential oils (and other ingredients) that should be avoided, please see:
List of Ingredients to Avoid
Abstract
Even though several plants can improve the female reproductive function, the use of herbs, herbal preparations, or essential oils during pregnancy is questionable. This review is focused on the effects of some essential oils and their constituents on the female reproductive system during pregnancy and on the development of the fetus. The major concerns include causing abortion, reproductive hormone modulation, maternal toxicity, teratogenicity, and embryo-fetotoxicity. This work summarizes the important studies on the reproductive effects of essential oil constituents anethole, apiole, citral, camphor, thymoquinone, trans-sabinyl acetate, methyl salicylate, thujone, pulegone, β-elemene, β-eudesmol, and costus lactone, among others.
Keywords:
Anethole; apiole; camphor; citral; essential oils; methyl salicylate; pregnancy; pulegone; thujone; trans-sabinyl acetate.
Noteworthy paragraph in study:
Another major concern about essential oils and their constituents is mimicking, interfering with, or antagonizing the action of reproductive hormones, which in turn could disrupt the reproductive and developmental processes [11]. Some EO constituents could affect the outcome of pregnancy through causing maternal toxicity, teratogenicity, embryo-fetotoxicity, or anti-angiogenicity [12]. Since angiogenesis is essential for a successful pregnancy, anti-angiogenic oil constituents carry the risk of causing preeclampsia, growth restriction, and fetal death [13,14]. Moreover, at high doses, teratogenic oils or components can cause birth defects of a structural nature that arise during embryonic development [15]. Generally, EO components can cross the placenta to the fetal circulation due to their low molecular weight, protein binding ability, and lipophilicity and can cause fetotoxicity [16]. Components that cross the placenta are more likely to affect the fetal central nervous system (CNS) since it is underdeveloped [17]. Unsaturated compounds like cinnamaldehyde, citral, and β-pulegone act via interacting with the lipids in embryo cell membranes [18]. Subcutaneous injection of 1,8-cineole (at 500 mg/kg for four days) to pregnant rats affected the fetal liver enzymes activity [19]. Similar to crossing the placenta, most flavor and EO constituents are expected to pass into breast milk via passive diffusion [20]. In lactating mice, constituents of sandalwood oil were able to pass to maternal milk and affected infant hepatic metabolic enzymes [21].
Conclusion:
In summary, if essential oil constituents are present in the mother’s circulation, they are expected to reach the fetus and exert some toxic effects.
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