Evening primrose oil: “Don’t use it if you are pregnant?”

Note: After I published this article, it came to my attention that there was one other study on the oral use of EPO in pregnant woman.  You can read more about this second study in the comments section below.


Many moms and midwives use evening primrose oil (EPO) for cervical ripening. So I was absolutely shocked at the complete lack of evidence on the effectiveness and safety of EPO use among pregnant women. There is one study that examined the oral use EPO and it’s ability to ripen the cervix during pregnancy. It concluded EPO didn’t work as we expected it to and further, women who took EPO were more likely to experience a whole host of complications. Shockingly, there are no studies on the vaginal use of EPO and it’s effect on ripening the cervix during pregnancy. In short, there is insufficient clinical evidence documenting the risks and benefits of EPO and without that information, should pregnant women take it?

The two studies that have examined cervical ripening via oral EPO

Paula Senner gives an excellent review of this single study in her Quantitative Research Proposal entitled, “Oral Evening Primrose Oil as a Cervical Ripening Agent in Low Risk Nulliparous Women” (emphasis mine),

A study by Dove and Johnson (1999) investigated the use of evening primrose oil on the length of pregnancy and selected intrapartum outcomes at an American free-standing birth center in low-risk nulliparous women. More specifically, the study examined the effect of oral evening primrose oil on length of pregnancy, length of labor, incidence of postdates induction, incidence of prolonged rupture of membranes, occurrence of abnormal labor patterns, and cesarean delivery.

A two group retrospective quasiexperimental design was conducted on a sample drawn from the records of all nulliparous women at a free-standing birthing center over a seven year period from 1991 to 1998. All of the records were screened for accurate gestational age dating, cephalic presentation, low risk status and delivery between 38 and 42 weeks gestation. The study group consisted of 54 women who took oral evening primrose oil in their pregnancy (500 mg three times a day starting at 37 weeks gestation for the first week of treatment, followed by 500 mg once a day until labor ensued), and the control group was composed of 54 women who did not take anything. Antepartum and intrapartum records of all women were reviewed focusing on the above identified criteria.

Differences between measured variables of maternal age, Apgar score, birth weight, length of pregnancy, and length of labor were tested… Results showed no significant differences between the evening primrose oil group and the control group on age, Apgar score, or days of gestation (P>.05)… This retrospective chart review showed no benefit from taking oral evening primrose oil for the purpose of reducing adverse labor outcomes or for reduction of length of labor.

The study’s abstract gives us more details on the its findings (emphasis mine):

Findings suggest that the oral administration of evening primrose oil from the 37th gestational week until birth does not shorten gestation or decrease the overall length of labor. Further, the use of orally administered evening primrose oil may be associated with an increase in the incidence of prolonged rupture of membranes, oxytocin [Pitocin] augmentation, arrest of descent, and vacuum extraction.

The second study found that while women who took EPO experienced a greater degree of cervical ripening, that did not result in a shorter pregnancy or labor: “There was no significant difference in the interval from onset or end of treatment to onset of labor between the two groups” (Ty-Torredes, 2006).

So one study on oral EPO found that it doesn’t work as we thought it did and it offers considerable risks.  The other study found that it does result in some cervical ripening, but that did not translate into shorter pregnancies or labors.

As a result, a December 2009 article published in the American Family Physician recommended,

The use of evening primrose oil during pregnancy is not supported in the literature and should be avoided.

Medline Plus, a website published by the US National Library of Medicine and the National Institutes of Health, published an April 2012 article on EPO.  Medline echoes the sentiments of the American Family Physician article when it said there was,

insufficient evidence to rate effectiveness for [EPO during pregnancy and] research to date suggests that taking evening primrose oil doesn’t seem to shorten labor, prevent high blood pressure (pre-eclampsia), or prevent late deliveries in pregnant women… [Further,] taking evening primrose oil is POSSIBLY UNSAFE [their emphasis] during pregnancy.  It might increase the chance of having complications. Don’t use it if you are pregnant [emphasis mine.]

Bleeding issues could complicate cesareans

Research on the use of EPO for other aliments among non-pregnant people has suggested there could be a possible association between the use of EPO and bleeding problems during surgery. As a result, Medline recommends that people don’t use it at least 2 weeks before a scheduled surgery.

This poses a special problem for women using EPO during the last weeks of pregnancy. Since we cannot predict who will have a vaginal birth and who will have a cesarean, it is important to consider that EPO could contribute to hemorrhage during a cesarean and possibly even during a normal vaginal delivery. We just don’t know because there is a lack of data.

Dosages and mode of delivery

Another hole in the research and our knowledge relates to dosage.  I see women reporting an incredible range of dosages on the internet.  What is safe?  There are no clinical studies documenting how much women should take.  Maybe X dose of EPO is good, but Y dose introduces XYZ risks.  How long should women take EPO?  The last month of pregnancy?  The last two weeks?  (Remember, we just read how there is a possible bleeding issue.)  Should they take it twice a day or once a day?  Does the body absorb or metabolize EPO differently if it is administrated vaginally or orally?  Does it make a difference if the woman using EPO has a scar on her uterus?  Or multiple scars?  We just don’t know the answers to these questions.

What about our bodies’ innate ability to birth?

It comes down to the fundamental question: Do our bodies need something to help us go into labor? Many natural birth advocates reject the routine use of Pitocin augmentation during labor because they say our bodies know how to birth.  Yet it’s often women from this same mindset that use EPO. Either our bodies work as is, or they don’t.  Either we need something to help us go into labor – whether that is EPO or Pitocin – or we don’t.

Are we less leery of EPO because it comes from a flower?  Because midwives suggest it more than OBs?  Because we can purchase it over the counter?  Because it’s a pill, not an injection?  Because we can administer it to ourselves in the comfort of our home?  Because it’s not produced by “big pharma?”  Because it is used so routinely that no one questions it?  Or is it simply because we all assume since everyone takes it, the evidence must be on the side of EPO?

On (the lack of) evidence: Holding ourselves to the same standard

When I have shared the lack of evidence on EPO’s ability to ripen cervixes or prepare a woman’s body for labor, sometimes women reply with “But there is none [evidence] to suggest it won’t [help] either…….” American OBs used this same rationale when they induced scarred moms with Cytotec in the 1990s. There were no published medical studies on Cytotec induction in scarred women, so we didn’t know the risks and benefits. But people used it because we knew it caused uterine contractions. What can go wrong, right?

But the problem is, when there is a lack of clinical evidence on large populations of women, we are sometimes surprised with dire outcomes that no one could have predicted as was the case of Cytotec.  We cannot look back at that period and think, “How could they have done that” when we are now doing the same thing with EPO: using a chemical without evidence of its benefits and harms.

Some rail against “the medical system” because Pitocin/ultrasound/etc hasn’t been “proven safe,” yet we use EPO with no evidence that it does what we think it does, no evidence that it is safe, and the limited evidence we do have says that it’s associated with a variety of complications.

As Hilary Gerber D.O. aka Mom’s Tin Foil Hat says,

As someone who spent many years in the natural supplements industry, I agree that we need to hold natural products to the same scrutiny.

Also, most EPO is extracted with solvents like hexane. I am much more supportive of natural products or interventions that have been used in that form or method for generations (e.g. sexual intercourse at term, ingesting a substance that is a common food item, etc) than a chemically extracted, concentrated, unstudied substance.

Anecdote vs. evidence

OBs who used Cytotec on scarred women in the 1990s inevitably would have said, “I haven’t had a bad outcome yet,” and I suspect that many people who use EPO now would say the same thing.  When we have one woman who used EPO and had an arrest of descent, do care providers recognize that this could be as a result of the EPO?  When we have one women who used EPO and it worked as expected, how can we determine her labor progressed because of the EPO?

When you have a small sample size, it’s hard to make a connection.  It’s even more difficult to connect EPO to it’s possible list of complications when not many care providers are aware of the lack of evidence on EPO and the findings of this one lone study.  Is our limited experience, with relatively few patients, without meticulous record keeping that can detect patterns across groups of patients, sufficient evidence?  I don’t think so.  We would likely need thousands of women in order to create a sample size powerful enough to detect – or rule out – common and more rare EPO complications in addition to answering the many questions I posed above.

Take away message

I’m not saying to use EPO or not.  I’m simply pointing out how little we know about this commonly used substance and questioning if that should make a difference in how we view and/or use it.

There is limited evidence on EPO’s ability to ripen the cervix and aid with labor.  We have two studies on the oral use of EPO that looked at this question and none on the vaginal use of EPO among pregnant women.  This is reason enough to not use it.

We have no evidence on an appropriate or safe dosage (if that exists).

We have no evidence on the risks and benefits of oral vs vaginal administration.

In order to make the association between EPO and complications, care providers need to be aware of the complications with which EPO may be associated.

Let’s review the research that does exist.  One study found that EPO doesn’t ripen the cervix and poses considerable risk.  Another study found that EPO does ripen the cervix but those women did not go into labor sooner than the women that didn’t take EPO. We need more large studies to confirm or refute the notion that EPO = ripen cervix = shorter pregnancies. Without that information, we are using a product that we know very little about.


Bayles, B., & Usatine, R. (2009, Dec 15). Evening Primrose Oil. American Family Physician, 80(12), 1405-1408. Retrieved from http://www.aafp.org/afp/2009/1215/p1405.html

Dove, D., & Johnson, P. (1999, May-Jun). Oral evening primrose oil: its effect on length of pregnancy and selected intrapartum outcomes in low-risk nulliparous women. Journal of Nurse-Midwifery, 44(3), 320-4. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10380450

Gerber, H. (2012, November 13). Facebook comments on evening primrose oil.

McFarlin, B. L., Gibson, M. H., O’Rear, J., & Harman, P. (1999, May-Jun). A national survey of herbal preparation use by nurse-midwives for labor stimulation. Review of the literature and recommendations for practice. Journal of Nurse Midwifery, 44(3), 205-16. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10380441

Medline Plus. (2012, Apr 10). Evening primrose oil. Retrieved from Medline Plus: A service of the U.S. National Library of Medicine & National Institutes of Health: http://www.nlm.nih.gov/medlineplus/druginfo/natural/1006.html

Senner, Paula. (2003, December). Oral Evening Primrose Oil as a Cervical Ripening Agent in Low Risk Nulliparous Women. Retrieved from Frontier School of Midwifery and Family Nursing, Philadelphia University: http://www.instituteofmidwifery.org/MSFinalProj.nsf/a9ee58d7a82396768525684f0056be8d/f44c26c0836acbb585256dd1006b2a22?OpenDocument

Ty-Torredes, K. A. (2006). The effect of oral evening primrose oil on bishop score and cervical length among term gravidas. AJOG, 195(6), S30. Retrieved from http://www.ajog.org/article/S0002-9378%2806%2901323-8/fulltext

Wagner, Marsden. (1999). Misoprostol (Cytotec) for Labor Induction: A Cautionary Tale. Retrieved from Midwifery Today: http://www.midwiferytoday.com/articles/cytotecwagner.asp

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36 thoughts on “Evening primrose oil: “Don’t use it if you are pregnant?”

  1. Angie Bond

    I am so glad you posted this! We used EPO supplements as anticoagulants for a couple of the vet clients that wanted all natural treatments for their pets and it worked superbly as a blood thinner. It was recommended as a natural alternative to blood thinners for my mother in law after her hip replacement this spring and per her blood work, seemed to be just as effective as heparin (I wish I could remember the dosage or had better sources for you!). So I have been meaning to look for existing data, as it was recommended by my midwife and is part of her routine recommended care. Thanks for your efforts and providing such easily accessible references for informed care!

  2. Angie Bond

    Some more thoughts that have come up this morning regard the possible effects to infants, since birth and postpartum are about baby, too!
    How much of the EPO is metabolized by the placenta and how much crosses the placental barrier?
    How do neonatal kidneys process EPO?
    Will this effect jaundice, potentially?
    Will the metabolism of EPO potentially effect the metabolic screen?
    Since EPO is implicated as possibly being a blood thinner, how would this effect bruising for infants who may require forceps or vacuum?
    What happens if baby requires a blood draw, tongue tie clipping, circumcision or some other normally minor procedure and then doesn’t clot properly?

    If baby is exposed to EPO for weeks in utero while mom is taking it, there are a lot of questions that have not even been addressed, let alone data to support a recommendation. So many questions! A natural intervention is STILL an intervention, and still poses potential complications while not necessarily being safer.

  3. Shawn

    Interesting article and you have well-founded points about the research.

    But you have no knowledge about EPO or how fatty acids work in pregnancy. The concern about increasing Omega 3 fats was a potential for prolonged bleeding times and guess what? It doesn’t happen because the body knows it is pregnant and compensates. The body will use the components of these oils to thin the blood…IF it is needed. Aspirin (a wonder drug according to many), on the other hand, kills platelets and it takes the body 17 days to make more. The oils turn functions on and off.

    When I was a midwife, some of my clients consumed 4,000 mg of EPO throughout pregnancy and the had awesome, fast, easy labours. I was quite familiar with the Journal of Nurse Midwifery article and I agree – do not start EPO at 37 weeks. Start earlier. Any oil/fat needs time to be incorporated into the tissue – often months.

    Your knickers are in a knot about a non-issue. EPO will not bring on labour (nor does fish oil). Both oils, however, help to encourage stretchy tissue and reduce the incidence of prolonged labour. I encourage women to increase Omega 3 intake in pregnancy and for breastfeeding because A) there is a lot of research, B) the fetal/newborn need for DHA is considerable and C) it makes a huge difference for birth.

    EPO has preformed GLA in it that some people cannot create with intake of the parent fatty acids. A very small percentage of people do not do well on a GLA rich supplement. The message is to listen to your body. Personally, I will take a natural intervention over prolonged labour/epidural/caesarian any day.

    1. Jen Kamel Post author


      Thank you so much for your comment.

      “The concern about increasing Omega 3 fats was a potential for prolonged bleeding times and guess what? It doesn’t happen because the body knows it is pregnant and compensates….Both oils, however, help to encourage stretchy tissue and reduce the incidence of prolonged labour.”

      Are their studies looking at EPO/GLA in pregnant women measuring bleeding issues or prolonged labour? I couldn’t find any other than Dove which found it was associated with prolonged rupture of membranes.

      “Any oil/fat needs time to be incorporated into the tissue – often months.”

      That would make for another interesting study – comparing outcomes based on how long EPO/GLA is consumed prior to delivery.

      “A) there is a lot of research”

      Could you share it with me? If I have written something that is inaccurate, I would be happy to amend the article if there is evidence that I have missed. I found a handful of other very small studies on EPO in pregnant women, but none of which were measuring it’s ability to induce labor or ripen the cervix. They were mostly looking at pre-eclampsia and if EPO in conjunction with fish oil made a difference.



      1. Francine

        Hi Jen, I am wondering why you have not updated your article based on the information in the 2006 AJOG study.

        1. Jen Kamel Post author


          I swear, there is no conspiracy. I wish I could update all articles with new information as I come across it, but that is simply not possible due to my existing personal and professional obligations. However, your comment reminded me that this item was on my ever expanding to do list, so I finished it up today.

          To be clear, the 2006 study found that EPO was associated with a greater degree of cervical ripening. However, that cervical ripening was not associated with shorter pregnancies or labors, so that makes two of two oral EPO studies that do not support the idea that EPO will help bring on labor or result in a quicker labor.



    1. Jess

      Note that this appears to be an abstract from a conference and not a peer-reviewed paper.

  4. Stacy L.

    I am SO glad to have this information. It is something I have questioned for years and have not been able to verbalize it correctly for my clients. Thank you so much!!!

    1. Jen Kamel Post author

      Hi Sarah!

      I link to all the sources throughout the article, but added a list of sources at the end this morning for simplicity’s sake.



  5. Mandi

    Thank you for posting this. As a doula, I find it confusing that natural birth advocates tell women to listen to their bodies and that we’re made to birth and that birth is least dangerous when undisturbed but then, often in the very same breath, advise them to take supplements. I’m all for interventions that work, but I cannot in good faith advise a client to research “bad” interventions suggested by their doctors such as inductions and amniotomies, but not to research “good” interventions suggested by their midwives. I appreciate the indescriminate use of research.
    Mandi The Doula

  6. gail hart

    The same simple standard should be used by all working with women in pregnancy, whether doctor, midwife, or educator.
    The standard should be “Advise no medication or intervention unless it is proven to be effective, and proven to be harmless.”

    By that standard, DES would never have been used, and certainly not cytotec/misorprostol, and countless women would have been spared harm.

    Concerning EPO (GLA), where is the evidence showing it is effective? The study by Karen Alessandra Ty-Torredes showed NO BENEFIT because there was no differences in length of labor or length of pregnancy in the group of 71 women studied.
    There was a statistical difference in consistency (ripening) of the cervix, but it did not translate into any effect on outcome. And there is the glaring problem in the study that it was not stratified by nullip vrs multip!

    There have only been a few studies on using EPO or GLA. Not one of them showed any benefit. At least one showed possible harm. The risk of hemorrhage is recognized in other trials and surgeons suggest eliminating it before operations to prevent increased blood loss.

    How can I as a midwife recommend a substance when the few studies show it is not effective, not beneficial and may be harmful? If our physician colleagues did this would would lambaste them for experimenting on women (again) and risking them harm!

    And what woman would use a substance if she were given ‘informed choice’ as “this substance has not been shown to be effective and may cause difficulties in labor”, yet this is the only accurate information we can tell her about GLA/EPO.

    Thinking that it must be good because we’ve seen women have nice labors who use EPO/GLA is a weak argument unless we have never seen nice labor in women who don’t use it!

    Or have never seen a poor labor in a woman who did use it. Anecdotes often lead us into misinformation. Fortunately most of the time it does not matter. MOST women will have ‘nice labors’ and end their pregnancies well, no matter whether they take out special vitamin pill or herbal blend or give them a daily green jelly bean. The process is designed to go well, and this makes it difficult to detect the value of any preventive or ‘tonic’ treatments.

    It takes large numbers to see effectiveness, although harm often shows with a smaller sample.

    To show effectiveness with EPO/GLA the study size should probably be at least 200 primes, divided into users or non-users, and followed by similar practitioners.

    Such a study would have to first prove that EPO/GLA is safe to use in pregnancy.
    With the previous small study as evidence of harm, it will be quite a hurdle to overcome.

    But.. if the safety issue is resolved, THEN a nice large study can be done…

    and if the studies show that EPO is safe and effective, only THEN should we consider recommending it. Not before!

  7. Lori Doty

    I had significant immediate postpartum bleeding. I wonder now if it was due to the fact that I did use EPO vaginally for about 2 weeks prior to both births.

  8. Vince

    Is there any more recent studies or doucumentation? I think a correct balance must be attained for EPO to be beneficial. Too much is always dangerous. Looking forward to more developments.

    1. Jen Kamel Post author


      I believe the two studies mentioned above are the only two looking at childbirth and EPO.



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  10. Kateri

    I took 1000mg of evening primrose oil as suggested by my Doctor starting at 38 weeks. I have have 3 easy, fast (compared to some) and healthy babies. I think that lack of studies is because it is not harmful so why bother. I will take it with my next pregnancies for sure. There are a lot worse things we could do than take a herb like evening primrose oil.

  11. Amanda

    Thanks for this. It is so hard to find any kind of scientific approach to natural remedies, and I have the same attitude that avoiding interventions and medications during pregnancy should extend to “natural” remedies unless they have demonstrated benefits and safety. A midwife recommended EPO to me yesterday; I did fine in my previous pregnancy and labor without it, and I think I’ll skip it this time, too.

  12. Rose

    Wow, and I was just about to try and find a local source for EPO. No thank you!

    Thanks for looking into this more closely!

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  14. Courtney

    Thanks for this. Like Lori, I had severe immediate postpartum hemorrhage–about 1 liter–that almost necessitated transfer to a hospital (midwives got it under control w/pit drip and uterine massage). Don’t know if the EPO I used caused or contributed to this, but I am pregnant with our 2nd now, and definitely NOT using it this time around just in case.

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  16. Does it help in a missed miscarriage?

    I found out yesterday that my baby died at 8 weeks (I should be now 11 weeks). I’ve had some bleeding and small clots coming out, but no cramps at all. I do not want to go through a surgical procedure so I am supposed to wait until miscarriage occurs naturally. However, I am not sure it will. Do you think evening primrose oil could help in my case, as I am not afraid for the baby (it is already gone…). I would just like to have it naturally but I would like something to speed it up or make it easier. Thank you so much for your help.

    1. Jen Kamel Post author

      I am not a medical professional, but I do not believe EPO would help you in this situation.

      I am so sorry for your loss. <3



  17. Lorena

    I took EPO while pregnant with my son and I wasn’t supposed to have him until around 2-3 o clock I had him at 1135am sooooo it worked for me theres my own personal study….

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  19. Julie

    @Lori Doty
    Just wanted to comment that I had immediate bleeding that seemed to take a while to stop after my 3rd child was born. I have never taken EPO but with my now 4th pregnancy I am interested in not tearing at birth so I am looking into it. I just took a small amount and it seems to have eased my PMS like symptoms within a couple of hours. I am wanting a very different birth this time without any intervention. I have been induced twice of my 3 SVDs. I definitely do not want to be induced with pitocin or have my water broken this time. I do not want to have to lie on my back the whole time because the health care team force me to. I also do not want to be counted at and forced to push when I don’t feel like it. I have a new outlook on birthing since I watched “the business of being born” on Netflix. I felt very emotional about the film.

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  21. Joelle

    I thought the main benefit of EPO was making the cervix stretchy, therefore minimising tearing yet this isn’t mentioned at all?

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  23. amy

    I took evening prime rose oil. Friday I was not ripe at all i starting takin them after my appt. Had the baby monday @37 weeks.easiest labor ever. Will definatly use again very effective

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