Do Essential Oils Cross the Placenta?

By Stephanie McBride

​Despite the ever-growing body of research on Essential Oils, there is only a small amount of study conducted on Essential Oil use during pregnancy- this, in part, owing to the question of whether or not it is ethical to conduct research on pregnant women. 

The quick answer, though, is that yes is very likely that many Essential Oils do cross the placenta, as well as cell membranes, the blood-brain barrier, and into breast milk.  Because of this, it is especially important to be mindful of Essential Oil purity and dosages when using Essential Oils to help mitigate the many discomforts that arise during pregnancy. (Tillett & Ames, 2010)

This is how it is understood.  The placenta provides a natural barrier against positive and neutral molecules and against molecules that weigh 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 some 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.  In fact, many may have a positive effect.  In addition, the immaturity of the fetal liver may offer a degree of protection since fetuses are not capable of metabolizing chemical compounds into more toxic forms, a process that requires phase two liver enzymes.

The incredible benefits of using Essential Oils during maternity far outweigh any effort it may take to understand quality and basic safety guidelines.  This simple, lovely practice has the potential to change someone's outlook, quality of life, or length of labor with little risk of harm, but there are a few things to keep in mind when adapting Essential Oil use for maternity.   First is the consideration of quality which, in fairness, is an important factor for safe and effective use at any phase of life.  The quality and purity of most Essential Oils are compromised because the majority of oils are produced strictly for their scent, not for therapeutic purposes.  In addition, there is little regulation over Essential Oil quality,  For example, the U.S. government does not oversee Essential Oil quality except to stipulate that 5% of a product be pure Essential Oil to be labeled “pure”.  This is a disappointment to many Essential Oil enthusiasts, who believe that the integrity of Essential Oil quality is at the heart of aromatherapy.  It is the level of quality that distinguishes Essential Oils used for therapy from, say, public bathroom air freshener!  For more information on this topic, please see my website and other blog entries.
The second thing to consider when adapting Essential Oil use for maternity is dosage and concentration.  Generally speaking, women have more sensitive skin during pregnancy, are more affected by sun sensitizing Essential Oils (like citrus-derived oils), and should be mindful of which oils are recommended for their particular phase of pregnancy.  To lessen overall exposure and its unknown effects on the fetus and infant, it is prudent to avoid the oral use of Essential Oils during pregnancy and, conservatively, while nursing.  

Here are some tips for safe use during pregnancy:

• Use only therapeutic-quality Essential Oils.
• Dilute Essential Oils to 1% concentration for massage (one drop per teaspoon of carrier oil) as a starting point.
• Test diluted oils on the wrist before first use and watch for signs of irritation for up to 24-hours.
• Use oils that are recommended for each specific phase of maternity (see recommend oils).
• Avoid oral use during pregnancy and postpartum, unless under the care of a qualified professional.

To learn more on this topic, visit my website, Daily Nectar Essentials.

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