How Safe Is Evening Primrose Oil During Pregnancy – Benefits & Side Effects?

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Medically reviewed by Kimberly Langdon, MD

The arrival of your newborn is one of life’s most precious moments, but what if you have passed your due date with no sign of labor? Anticipating the arrival of your bundle of joy may give you more jittery feelings than joy. So how safe is evening primrose oil during pregnancy?

Perhaps you have heard a friend saying that evening primrose oil helped them jumpstart labor to deliver a healthy newborn. Many pregnant women use evening primrose oil to induce labor and speed up the ripening of the cervix. 

Read on to determine how safe evening primrose oil is during pregnancy, how effective its use is on cervical ripening and labor induction, and when to start taking evening primrose while pregnant.

How Safe Is Evening Primrose Oil During Pregnancy?

According to the National Center for Complementary and Integrative Health (NCCIH[1]), evening primrose oil (EPO) may be safe for use during pregnancy to induce labor and breastfeeding, while the evidence is not conclusive. Pregnant women can start administering EPO either orally or inserted into the vaginal from week 38 of pregnancy until birth. 

The scientific research behind the safety of evening primrose oil to induce labor during pregnancy is mixed. Many pregnant ladies seem to use evening primrose oil during pregnancy with no issues, while some have linked its use during pregnancy to an increased risk of complications with labor and delivery[2].

What Is Evening Primrose Oil?

Evening primrose oil capsules are herbal supplements derived from the seeds of the evening primrose plant, which consists of omega-6 essential fatty acids, including linoleic acid and gamma-linolenic acid (GLA), and vitamin E.

Evening primrose oil supplements typically exist in a gel cap form and can be purchased at your local pharmacy or health food stores. Most people take evening primrose oil capsules orally in doses between 500 to 2000 milligrams daily. But women during pregnancy can also administer evening primrose oil as a vaginal capsule or extract its oils and apply it onto the vagina towards the end of pregnancy to induce labor.

Evening Primrose Plant

This plant is found in parts of Europe and Asia but is native to North and South America. This yellow flower is commonly known as evening star or sundrop as it closes during the day and opens at sunset. 

Traditionally, the Native Americans used these plants for treating bruises and inflammation of the skin. Today, evening primrose oil is also used to treat inflammatory conditions[1], such as atopic dermatitis and rheumatoid arthritis. 

Does Evening Primrose Oil Help Induce Labor?

Although many midwives and alternative health practitioners worldwide recommend the use of evening primrose oil[2] to believe that it speeds up the ripening of the cervix and shortens labor, its effectiveness has not been well studied. 

According to American Family Physician, evening primrose oil may help the cervix soften and thin out[3] in preparation for childbirth. Other studies also show that the linoleic acid and GLA found in evening primrose oil are pre-cursors to anti-inflammatory eicosanoids[4] and may trigger a prostaglandin response in the body, which helps to ripen the cervix and help induce labor. However, as an anti-inflammatory, prostaglandin release would be decreased.

There is currently no evidence strong enough to support the use of evening primrose oil on cervical ripening or on initiating uterine contractions in labor. Still, studies give researchers food for thought. 

Mixed Research Results

Research[5] from a clinical trial showed that women at week 40 of pregnancy who took 1000 milligrams of evening primrose oil twice a day orally for one week did not affect the Bishop’s score, the ripening of the cervix, nor the duration of labor.  

However, a small recent randomised clinical trial published in Nursing Practice Today on the effect of vaginal evening primrose oil on term nulliparous women revealed different results. The study[6] showed that vaginal use of evening primrose oil containing a daily dose of 1000 milligrams starting from week 38 of pregnancy until delivery could be used to ripen the cervix and shorten labor duration.  

The same study revealed the participants did not suffer any associated side effects, had a higher Bishop’s score upon admission for birth, and were less likely to receive oxytocin to induce labor. Although more studies are needed, the use of vaginal evening primrose oil could be a safe and effective way to ripen the cervix during late pregnancy and to induce labor. 

The Bishop’s Score

The Bishop’s score is a common way used by midwives and medical professions to evaluate the readiness of the cervix for labor. Not only does it measure the dilation and thinning of the cervix, but also cervical consistency and position, and how high the fetal head is in preparation for childbirth.

Is Evening Primrose Oil Safe During Pregnancy?

More research is needed to understand and evaluate the safety of evening primrose oil fully. At present, we can assess the use of evening primrose oil during pregnancy with only the limited data we have so far.

Positive Effects of EPO

Despite no concrete evidence of efficacy, midwives worldwide (apart from the U.S.) commonly opt to use evening primrose oil to help prepare the cervix for labor and delivery before using harsher chemicals. Using evening primrose oil may help avoid[6] the need to induce labor medically and help prevent its after-effects. 

Evening primrose oil is seen as a natural remedy, is relatively inexpensive, and easy to obtain through the local pharmacy or health food store. It is also generally well tolerated with only minor side effects. 

Adverse Effects of EPO

Like many dietary supplements, there is not much research into the long-term effects of taking evening primrose oil. Still, side effects[7] can include headaches and gastrointestinal problems, such as nausea and diarrhea. 

Although the side effects of evening primrose oil subside once you stop taking the supplement, a study reveals that women taking evening primrose oil during pregnancy may increase pregnancy complications, such as prolonged rupture of membranes[2], arrest of descent, oxytocin augmentation, and vacuum extraction. 

American Family Physician also suggests that evening primrose oil can act as a blood thinner and can affect platelet aggregation[3], although more research is needed to conclude this further.  

You may be feeling anxious about taking supplements or medicines during pregnancy, check out information about over-the-counter medications in pregnancy and is Tylenol safe for pregnancy

When To Start Evening Primrose Oil During Pregnancy

You can purchase evening primrose oil in capsules, which can be taken orally, inserted into the vagina, or applied topically to the vagina. 

Towards the last days or week of pregnancy, nulliparous women can insert a soft vaginal evening primrose capsule directly into the vagina or extract the oil from the capsules to apply onto the vagina.  However, safety of this regimen is unknown.

There is currently no standard dosage of evening primrose oil during pregnancy; however, most women consume up to 2000 milligrams per day from week 38 of pregnancy until birth. Never administer before week 37 of your pregnancy as there is a possibility that you may jumpstart preterm labor. 

Remember, you should always seek professional medical advice before starting any new supplement during any stage of your pregnancy, particularly if you are taking other medications. 

Other Uses of Evening Primrose Oil

According to the National Center for Complementary and Integrative Health (NCCIH), there is little evidence[1] to support the use of evening primrose oil for any medical conditions or to provide health benefits. 

Whether evening primrose oil works or not, it is widely used as an alternative therapy for the treatment and symptomatic relief in various medical conditions[5], such as neuropathy, rheumatoid arthritis, and psoriasis. 

Evening primrose oil is also used in many women’s health issues, such as cyclical breast pain (mastalgia), premenstrual syndrome, and menopause. But according to American Family Physician, evening primrose oil is not likely to be effective[3] in treating breast pain and premenstrual and menopausal symptoms. 

However, research suggests that taking evening primrose oil along with vitamin D during pregnancy may help to reduce symptoms[8] of gestational diabetes. If you do have gestational diabetes, make sure you get the green light from your doctor before starting any supplement. 

Alternative Ways For Inducing Labor

It is difficult to determine whether taking evening primrose oil alone helps to trigger labor as women in late pregnancy often combine trying different natural remedies to induce labor. Some other methods to induce labor naturally include:

  • Exercising
  • Walking up and downstairs
  • Drinking red raspberry leaf tea
  • Consuming castor oil
  • Eating spicy foods
  • Engaging in nipple stimulation, such as using a breast pump
  • Engaging in sexual intercourse 
  • Going for acupuncture

A study[9] that looked into complementary and alternative medicine to start labor concluded that evening primrose oil or castor oil is ineffective at inducing labor and possibly increases the risk of pregnancy complications.  

However, the same study found the use of nipple stimulation, acupuncture, and red raspberry leaf tea possibly beneficial for labor induction so perhaps you ca

Conclusion

  • Evening primrose oil is a natural herbal remedy believed to ripen the cervix and induce labor in pregnant women past their due date. 
  • At the moment, research suggests there is insufficient scientific evidence to approve or disapprove of the use of evening primrose oil during pregnancy for cervical ripening or inducing labor. 
  • Many women worldwide use evening primrose oil during pregnancy without issues, while studies show some encounter labor complications. 
  • A small study published in Nursing Practice Today showed the use of vaginal evening primrose oil capsules inserted into term nulliparous women may help to induce labor, but more research is required. 
  • Although evening primrose oil is used for many medical conditions, such as atopic dermatitis and breast pain, there is little evidence of its effectiveness.
  • If you are past your due date, there are many other ways to try to induce labor naturally, with nipple stimulation and red raspberry tea leaf drinks being more promising. 
  • Remember to always get the green light from a healthcare professional before starting any new supplements at any stage during pregnancy, and particularly if you are past your due date and want to speed up the process.  


+ 9 sources

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  1. Evening Primrose Oil. NCCIH. Published 2013. Accessed May 21, 2021. https://www.nccih.nih.gov/health/evening-primrose-oil
  2. ‌Dove D. Oral evening primrose oil: Its effect on length of pregnancy and selected intrapartum outcomes in low-risk nulliparous women. Journal of Nurse-Midwifery. 1999;44(3):320-324. doi:10.1016/s0091-2182(99)00055-5
  3. Bayles B, Usatine R. Evening Primrose Oil. American Family Physician. 2021;80(12):1405-1408. Accessed May 21, 2021. https://www.aafp.org/afp/2009/1215/p1405.html#afp20091215p1405-b15
  4. Timoszuk M, Bielawska K, Skrzydlewska E. Evening Primrose (Oenothera biennis) Biological Activity Dependent on Chemical Composition. Antioxidants. 2018;7(8):108. doi:10.3390/antiox7080108
  5. Kalati M, Kashanian M, Jahdi F, Naseri M, Haghani H, Sheikhansari N. Evening primrose oil and labour, is it effective? A randomised clinical trial. Journal of Obstetrics and Gynaecology. 2018;38(4):488-492. doi:10.1080/01443615.2017.1386165
  6. Najafi1 M, Loripoor M, Saghafi Z, Kazemi M. The effect of vaginal evening primrose on the Bishop score of term nulliparous women. Nursing Practice Today. Published online December 2, 2019. doi:10.18502/npt.v6i4.1942
  7. Mahboubi M. Evening Primrose (Oenothera biennis) Oil in Management of Female Ailments. Journal of Menopausal Medicine. 2019;25(2):74. doi:10.6118/jmm.18190
  8. Jamilian M, Karamali M, Taghizadeh M, et al. Vitamin D and Evening Primrose Oil Administration Improve Glycemia and Lipid Profiles in Women with Gestational Diabetes. Lipids. 2016;51(3):349-356. doi:10.1007/s11745-016-4123-3
  9. Hall HG, McKenna LG, Griffiths DL. Complementary and alternative medicine for induction of labour. Women and Birth. 2012;25(3):142-148. doi:10.1016/j.wombi.2011.03.006

Written by:

Christina Cheung

Medically reviewed by:

Christina Cheung holds a Master’s of Pharmacy from the University of Bath (UK) and is a freelance writer specializing in medicine and science. With over a decade of experience as a community and hospital pharmacist both in the UK and abroad, she has dealt first-hand with patients facing medical difficulties and decisions. She now writes to promote medical health and wellness to better the community. Christina also has a published science blog with a passion for inspiring and encouraging medicine and science for kids and students. While not writing, she can be found strolling through the country parks with her family and pet dog.

Medically reviewed by:

PubMed Central

Database From National Institute Of Health

U.S National Library of Medicine
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