**8. Essential oils in pregnancy and lactation**

The main concerns of the use of essential oils during pregnancy is related to the risk of chemical compounds crossing the placental barrier with direct effects on the product of conception, but also to the direct abortive effect. The use of essential oils during pregnancy is a controversial topic and one that is yet to be fully understood.

Some essential oils are abortifacients, being capable of inducing miscarriage/ abortion. Essential oils like persil oil (*Petroselinum sativum*) rich in apiole, pennyroyal oil (*Mentha pulegium*) rich in pulegone, plectranthus oil (*Plectranthus amboinicus*), Spanish sage oil (*Salvia lavandulifolia*) or savin oil (*Juniperus sabina*) rich in sabinyl acetate should be avoided during pregnancy (**Figure 5**). The amounts required to induce an abortion may also pose toxicity risks to the mother, including kidney and liver damage (could be the reason of pregnancy termination in pennyroyal oil case) or even death [12, 38].

Due to their chemical properties (low molecular weight, lipophilicity), it is likely that certain essential oil components could cross the placental barrier, reaching fetal circulation. Following a possible biotransformation into polar molecules, they can accumulate in the fetus due to a reduced glomerular filtration rate and low content of plasma proteins capable of binding xenobiotics [13, 38].

Essential oils should not be used in pregnancy (or breastfeeding) if they contain large amounts of the following components: (E)-anethole (aniseed-*Pimpinella anisum*, star anise-*Illicium verum*, fennel-*Foeniculum vulgare,* dill-*Anethum graveolens*), apiole (persil-*Petroselinum sativum*), β-eudesmol (cypress-*Cupressus sempervirens*), camphor (Spanish lavender-*Lavandula stoechas*), methyl salicylate (sweet birch-*Betula lenta*), pinocamphone (hyssop-*Hyssopus officinalis*), or thujone (mugworth-*Arthemisia vulgaris,* savin-*Juniperus sabina,* thuja-*Thuja occidentalis*) [12, 38].

**Figure 5.** *Chemical compounds responsible for the abortifacient effect.*
