Do Essential Oils Cross the Placenta?

Our post today is from guest blogger Stephanie Pearson. Stephanie Pearson has worked with herbal medicine for over 25 years and is a clinical herbalist, functional nutritionist, and clinical aromatherapist master, in process. She created an e-course, Essential Oils for the Birth Kit, that is a comprehensive, evidence-based, and unbiased five-hour course on using essential oil therapy during each phase of pregnancy and in infant care. See below for the e-course preview video.

close up of pregnant woman touching her bare tummy

Do Essential Oils Cross the Placenta?

Despite the ever-growing body of research on essential oils, there is only a sippy cup full of study conducted on essential oil use during pregnancy––this owing to the unethical nature of conducting research on pregnant women.

The quick answer, though, is that yes, many essential oils do cross the placenta (and cell membranes and the blood-brain barrier), which is why it is especially important to be mindful of dose and quality during pregnancy (Tillett & Ames 2010).

The placenta provides a natural barrier against positive and neutral molecules and molecules with weight more than 1000 atomic mass units (AMUs). Since essential oils weigh less than 250 AMUs and many are negatively charged, it is fair to imply that essential oils cross the placenta. Despite this, there is virtually no evidence that, when used correctly, essential oils have a negative impact on the fetus in utero. The immaturity of the fetal liver may even offer a degree of protection, since fetuses are not capable of metabolizing compounds into more toxic forms, a process which requires phase two liver enzymes (Tillett & Ames 2010).

It is an important side note that the U.S. government does not oversee essential oil quality except to stipulate that 5% be pure essential oil to be called “pure.” This is a disappointment to many essential oil enthusiasts, who believe that the integrity of essential oil quality is at the heart of essential oil therapy and is, indeed, what distinguishes this natural health modality from, say, public bathroom air fresheners.

Don’t give up on essential oils during pregnancy just yet; their incredible benefits far outweigh any effort it may take to understand safe use. Of 23 patients evaluated in a 2000 controlled study on lavender for anxiety during induction of labor, for example, a significant number of moms were found to have had reduced anxiety, headache, and interrupted sleep (Adams 2000). Sitz baths with lavender essential oil were found to significantly decrease inflammation and pain compared to the control group using povidone-iodine sitz baths (Complementary Therapies in Clinical Practice 2010). There are diapers-full of studies on pain relief during labor, reduced nausea during pregnancy, and other maternity-related topics as well. This simple, lovely practice has the potential to change someone’s outlook, quality of life, or length of labor with little risk of harm.

Essential oil authors and medical professionals, including Ron Guba, Robert Tisserand, and Jane Buckle agree that with attention to dose and quality, “it is more prudent to recommend that those which are potentially dangerous be avoided throughout pregnancy than to limit responsible use of essential oils during early pregnancy” (Tisserand).


To assure safe essential oil use during pregnancy, I recommend that you use only high- quality essential oils diluted to 1% concentration (one drop per teaspoon of carrier oil, or use one drop neat on the bottoms of the feet). It is also important that only the essential oils which are believed to be safe during pregnancy are used.

If you would like more information on using essential oils during pregnancy, try the following links:
Essential Oils for Pregnancy on the AromaTools™ Blog
Birth Kit Essentials by Stephanie Pearson on the AromaTools™ Blog
Books, brochures, and tear pads on
Stephanie Pearson’s E-course: Essential Oils for the Birth Kit

About the Author

StephaniePearsonStephanie Pearson has a unique distinction in her field for integrating traditional practices in nutrition and herbalism with principles of evidence-based research and constitutional medicine. She is a certified clinical herbalist, functional nutritionist, and clinical aromatherapist master (in process). Stephanie is a professional educator and presenter at universities and for wellness conferences and webinars. Her 25 years of botanical medicine study expand outside the classroom and cross-culturally, enriched by field studies in Native American, Western Eclectic, and Latin American herbalism.

3 thoughts on “Do Essential Oils Cross the Placenta?

  1. From what I understand, essential oil use during pregnancy should not affect milk supply after birth. As stated above, the peppermint oil may affect milk supply after delivery, but not before.


    • I’ve heard of peppermint possibly causing this problem but never lavender. Before blaming an oil be sure that there were no other possible problems. Stress, not enough fluid intake, prescription medications, poor diet. Many things can lead to poor milk supply but working with a lactation consultant can usually bring up milk supply very quickly. There are even essential oils that can help increase milk production. My daughter used oils several times to boost her milk supply. She managed to donate 1,000 ounces to babies in need of breast milk.

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