Essential Oils That Cause Miscarriages: Your Pregnancy Blacklist

They’re hyped as all-natural helpers for stress, sleep, and everything in between — essential oils are having a moment — a few drops of lavender on your pillow, peppermint in your diffuser, or eucalyptus in a bath bomb. But if you're pregnant (or trying), you’ve probably heard some mixed messages. Are essential oils safe during pregnancy… or can they actually trigger a miscarriage?

Here’s the short version: Some essential oils may increase the risk of miscarriage or complications in early pregnancy — especially when used in high concentrations, ingested, or applied directly to the skin without proper dilution. But not all oils are risky, and many can be used safely with the right precautions.

Let’s break it all down — the real risks, the ones to avoid, and how to keep your self-care routine pregnancy-safe.

What are essential oils, exactly?

Essential oils are highly concentrated plant extracts. Think of them as the most intense, potent version of a plant’s scent and chemical compounds. They’re used in everything from massage oils and skincare to cleaning products and aromatherapy.

Because they’re so concentrated, they’re powerful — and that’s where the caution during pregnancy comes in. Even a few drops can have strong physiological effects, like stimulating hormones, affecting blood pressure, or triggering muscle contractions (including in the uterus).

Can essential oils cause miscarriage?

There’s no solid evidence that occasional or diluted exposure to essential oils causes miscarriage in healthy pregnancies. But that doesn’t mean all essential oils are safe — especially in the first trimester, when the risk of miscarriage is already highest and the fetus is still developing its organs.

There are a few reasons why you might consider avoiding certain essential oils in pregnancy — especially the ones packed with compounds like thujone, camphor, methyl salicylate, pulegone, citral, apiole, and anethole. These ingredients have been shown (mostly in animal studies) to do everything from triggering uterine contractions and messing with your hormones to crossing the placenta and potentially harming fetal development (AKA embryotoxic or fetotoxic effects).

Some can even interfere with how the placenta forms new blood vessels — a process that’s crucial for keeping your baby nourished and safe. While most of this research is based on animal data (because, obviously, no one’s testing toxicity on pregnant people), it’s enough to raise red flags.

Some oils also contain compounds that act like hormones (called phytoestrogens), which may affect the delicate hormonal balance needed in early pregnancy.

That said, most of these risks are based on high-dose exposure, undiluted application, or ingestion — not using a diffuser with a few drops of oil.

There’s still not enough human research to give a green light across the board — so most experts advise avoiding certain essential oils altogether, especially in the first trimester.

What about natural essential oils?

Here’s where things get a bit shady. Even though some essential oils are labeled "natural," that doesn’t automatically make them safe in pregnancy. Many of these compounds are powerful enough to affect hormones, the uterus, or fetal development — especially if used in high doses or taken internally, regardless of whether they are “natural” or not.

Which essential oils are not safe for pregnancy?

Here are the essential oils most commonly advised against during pregnancy — especially during the first 12 weeks:

• Clary sage, sage, and Spanish sage: Contain thujone or sabinyl acetate — which, according to Dr. Caledonia Buckheit, OB/GYN, “...have reproductive toxicity signals in animals, making concerns about uterine stimulation and miscarriage risk in humans plausible (though haven’t been proven in humans).”

• Pennyroyal: Contains pulegone — “well documented link to maternal hepatotoxicity, historical use as an agent to promote miscarriage (abortifacient) is concerning — definitely avoid!”, as Dr. Buckheit explains.

• Wintergreen and sweet birch: High in methyl salicylate — teratogenic to animals in high doses.

• Aniseed, star anise, and fennel: Contain anethole — mimics estrogen, may disrupt hormones or implantation.

• Camphor: Found in sage and other oils — crosses the placenta and is neurotoxic at high doses.

• Lemongrass, lemon myrtle, and citral-containing oils: Citral has shown birth defect potential in animals, so avoiding use in pregnancy is advisable.

• Myrrh and black seed oil: Animal evidence suggests these compounds could negatively affect fetal growth due to anti-angiogenic properties.

• Parsley, rue, tansy, and wormwood: Historically used as abortifacients (substances that can induce a miscarriage), some confirmed toxic in animals. Avoidance in pregnancy is recommended.

• Rosemary: May affect blood pressure and stimulate menstruation, although evidence is weak for these claims — best to check this one with your doctor.

• Cinnamon bark: May cause uterine stimulation, although claims aren’t exactly well supported — another one to check with your doc.

• Basil (some types): Linked to liver cancer in high doses in rodent studies, although impact in humans isn’t known.

• Sage (Dalmatian): Contains thujone, which historically has been used to bring on a period — although human evidence is limited. Worth checking with your doctor.

• Juniper berry: May stimulate a period.

• Mugwort: Associated with miscarriage in traditional herbal medicine.

• Niaouli: Known to alter progesterone, h-hCG, and hPL levels in placental cells (not good).

• Orange (sweet orange): In in vitro studies, sweet orange oil was associated with increased production of estradiol, h-hCG, and hPL — hormones involved in pregnancy. While often considered gentle, Dr. Caledonia Buckheit, OB/GYN, notes that “these findings were seen at higher concentrations in lab settings, and it’s unclear how (or if) they translate to real-life use during pregnancy.”

• Tea tree: Shown in in vitro studies to stimulate hPL secretion, a hormone produced by the placenta that supports fetal growth. However, Dr. Buckheit emphasizes that “the clinical relevance of this effect at typical exposure levels remains unknown.”

• Ylang-ylang: Lab data suggest this oil may increase hPL levels, and one of its components — benzyl salicylate — was linked to a rise in h-hCG, again only at high concentrations. “We don't yet know what this means for the body when used in everyday aromatherapy,” says Dr. Buckheit.

Some of these oils are totally fine in skincare or body products in tiny amounts — but when in doubt, skip them or check with a qualified medical provider.

What essential oils cause uterine contractions?

The main concern with some essential oils is their ability to stimulate the uterus — either through muscle contraction or hormone-like effects. This is sometimes used intentionally to support labor when you're full-term, but it’s risky earlier on.

Higher-risk oils with credible uterotonic or abortifacient concern (based on historical use and nonclinical evidence):

• Pennyroyal
• Sage (thujone-rich varieties)

“These oils have the most consistent historical and preclinical evidence for uterine stimulation or abortifacient effects,” says Dr. Caledonia Buckheit, OB/GYN. “They should be avoided entirely during pregnancy, especially in concentrated forms.”

Possibly associated oils with limited, dose-dependent, and largely preclinical evidence:

• Clary sage
• Cinnamon bark
• Juniper
• Myrrh
• Oregano
• Rosemary
• Thyme

“For these oils, the data we have comes mostly from animal studies or cell models, often at high concentrations,” Dr. Buckheit explains. “They’re not proven to be harmful in typical aromatherapy use, but caution is still a good idea — especially during the first trimester.”

These are sometimes referred to as "emmenagogues" — herbs or oils believed to promote menstruation — which is exactly why they can be risky during pregnancy. Even topical or inhaled use in large amounts could theoretically cause uterine cramping or bleeding.

Are any essential oils safe during pregnancy?

Yes — when used properly and in moderation. Some essential oils are considered low-risk and may even help with common pregnancy complaints like nausea, fatigue, anxiety, and insomnia.

Safer options (especially after the first trimester) include:

• Lavender: Relaxing, gentle on skin.
• Chamomile (Roman): Soothing for stress and sleep.
• Ginger: May help with nausea.
• Peppermint: Can relieve headaches and nausea (avoid near the chest if breastfeeding).

As Dr. Buckheit explains, “A small amount after the first trimester is probably fine — data is more limited for lavender and Roman chamomile. But ginger and peppermint have the best safety data and support for use in small amounts in pregnancy.”

Just remember to always dilute essential oils in a carrier oil (like jojoba, almond, or coconut oil) before applying to skin, use diffusers sparingly in well-ventilated rooms, and avoid direct contact with mucous membranes or using oils internally. It’s also worth doing a patch test before use — pregnancy can make skin more sensitive than usual.

And, of course, speak to your doctor first.

First trimester vs. third trimester: Does timing matter?

Absolutely. The first trimester is the most critical time for fetal development — and the most sensitive to potential toxins or hormonal disruptions. Some experts even recommend avoiding essential oils altogether during the first 12 weeks unless medically advised.

After that point, your body and baby are more resilient — but caution is still important. Some oils (like certain types of sage) are best saved for late pregnancy or labor under the guidance of a doctor or midwife.

What about essential oils in bath bombs, candles, or skincare?

Good question — because essential oils are everywhere. The good news? Most bath bombs, lotions, candles, and skincare products only use essential oils in super tiny amounts (we’re talking less than 0.01%), and when used as directed, they’re generally not considered a risk during pregnancy.

That said, stronger or more concentrated products — like massage oils or homemade blends — haven’t been studied much in pregnancy, so they’re harder to vouch for. And while there’s no proven harm from using essential oils on your skin or in the air, experts can’t say they’re 100% safe either — especially in large doses or when used every day.

The real red flag? Ingesting essential oils (like drinking a detox blend or using them internally). That’s where case reports have linked oils to uterine contractions and even miscarriage — likely due to toxicity. So ingestion = hard no.

But using a bath bomb on occasion? Lighting a scented candle? Rubbing on a stretch mark cream that smells faintly of lavender? You’re probably fine. Just skip anything that’s super strong or overwhelming in scent, without a clear ingredient list, or labeled as “undiluted” or made with essential oils not recommended in pregnancy

When in doubt, look for products labeled pregnancy-safe — and stick to the “less is more” rule. Because comfort is key, but safety comes first.

When to call your doctor or midwife

If you’ve accidentally used a contraindicated essential oil — don’t panic. The chance of serious harm from a small exposure is very low.

That said, call your healthcare provider if:

• You experience cramping, bleeding, dizziness, or contractions after using an essential oil
• You’ve ingested essential oils (you can also contact Poison Control in these circumstances)
• You’re unsure whether a product or oil is safe for your stage of pregnancy

Your care team can guide you on what to avoid and what’s okay — and help you navigate that overwhelming "is this safe?" moment.

Navigating aromatherapy safely during pregnancy

Essential oils aren’t automatically dangerous — but they’re definitely not always harmless. Some can offer real benefits when used with care, while others may carry risks, especially in early pregnancy or if used in the wrong way. As Dr. Buckheit explains, “They should not be assumed to be harmless just because they are ‘natural’ or whatever they use in their marketing.”

There are legitimate concerns about the link between certain essential oils and miscarriage — and while more research is needed, the potential for hormonal disruption or teratogenic effects means it’s worth treading carefully. If you want to keep essential oils in your routine while you're expecting, it’s all about being cautious and informed. Steer clear of high-risk oils during the first trimester, avoid slathering them on undiluted, and limit diffuser use to short, occasional sessions in well-ventilated spaces. And honestly? This isn’t the time to wing it — check in with your healthcare provider if you’re unsure.

Aromatherapy doesn’t have to be off-limits — but pregnancy is not the time to go full witchy apothecary mode. Keep it simple. Keep it safe. You and your baby both deserve that.