We Don't Recommend Evening Primrose Oil for Labor Prep or Induction
If you're nearing your due date, chances are someone has mentioned evening primrose oil (EPO) to you — maybe a friend, a forum, or even a well-meaning provider. It's one of the most commonly used "natural" labor prep remedies out there, taken orally or inserted vaginally in the final weeks of pregnancy with the hope of softening the cervix and shortening labor.
Here's the thing: "natural" doesn't automatically mean "safe" or "effective." When we actually look at the research, evening primrose oil doesn't hold up as well as its reputation suggests — and there are real reasons to think twice before using it.
What Evening Primrose Oil Is Supposed to Do
EPO is extracted from the seeds of the evening primrose plant and is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid. The theory behind using it for labor is that GLA gets converted in the body into compounds that are precursors to prostaglandins — the same hormone-like substances your body naturally produces to ripen the cervix and trigger labor. Because of this, EPO has long been used by midwives and birth workers as a way to encourage cervical ripening before or around a due date.
It sounds reasonable on paper. But the actual clinical evidence tells a much messier story.
What the Research Actually Shows
A 2022 systematic review published in the journal Pharmacy pulled together every available study on EPO and labor — seven randomized placebo-controlled trials, plus additional case studies and observational research. The findings were underwhelming at best:
Results across studies were highly inconsistent. Some found a modest improvement in Bishop score (a measure of cervical readiness), while others found no difference at all compared to placebo.
One of the largest and earliest studies, a 1999 look at low-risk first-time mothers, found that EPO was actually associated with a longer labor, not a shorter one.
Several trials found no meaningful difference in the time between hospital admission and delivery, Apgar scores, or need for further induction.
The review's authors were blunt about it: EPO is absent from the clinical guidelines of major professional bodies, including the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine, and the American Society for Reproductive Medicine. Based on the available data, the authors concluded that EPO "cannot be recommended for parturition in peripartum individuals based on the principle of 'do no harm.'"
The Safety Concerns Are the Bigger Issue
Efficacy aside, the safety picture is where things get more concerning:
Bleeding risk. EPO has been shown to inhibit platelet aggregation, meaning it can interfere with your body's normal clotting process. This matters a lot heading into an event where postpartum bleeding is already a known risk. A published case report described a newborn who developed diffuse bruising and petechiae (small red/purple spots caused by bleeding under the skin) after the birthing parent used EPO both vaginally and orally — significant enough that the baby was admitted to the NICU for observation.
No established safe dosing. There is no standardized or guideline-recommended dose for vaginal or oral use. Studies used wildly different doses and durations — anywhere from 500 mg once to 2,000 mg twice daily, for anywhere from a single dose to several weeks. We simply don't know what an appropriate, evidence-based dose even looks like.
It's an unregulated supplement. In the United States, EPO is sold as a dietary supplement, which means it isn't FDA-approved or held to pharmaceutical manufacturing standards. Contamination, inconsistent potency, and impurities are real possibilities with any unregulated herbal product — a bigger deal when you're using something to influence labor.
It's not appropriate for everyone. EPO should be avoided by anyone with a bleeding disorder, anyone on blood thinners or antiplatelet medications, and anyone with a seizure disorder — categories that are easy to overlook when a product is marketed as gentle and natural.
Long-term outcomes haven't been studied. None of the existing trials looked at longer-term maternal or neonatal outcomes. We simply don't have the data to say EPO is safe beyond the immediate hours after use.
Our Take
We know the desire to "do something" in those final, uncertain days of pregnancy is real — and deeply human. But at Be Well Baby, our approach to birth prep is rooted in what actually has evidence behind it, not just what's popular in online communities or handed down as birth-worker folklore.
Evening primrose oil sits in a frustrating middle ground: the research doesn't consistently show it works, and what safety data does exist raises real questions about bleeding risk, both for the birthing person and the baby. When the potential benefit is uncertain and the potential risk is bleeding-related, that's not a trade-off we're comfortable encouraging.
If you're looking for ways to support your body as you approach labor, there are options with a much stronger evidence base and a much clearer safety profile — and we'd rather spend our energy helping you explore those.
Love,
Emily
Reference:
Hutcherson TC, Cieri-Hutcherson NE, Lycouras MM, et al. Systematic Review of Evening Primrose (Oenothera biennis) Preparations for the Facilitation of Parturition. Pharmacy (Basel). 2022;10(6):172. doi: 10.3390/pharmacy10060172. PMID: 36548328. Available on PubMed Central: https://pmc.ncbi.nlm.nih.gov/articles/PMC9787658/
This post is for educational purposes and isn't a substitute for individualized medical advice. Always talk with your midwife or OB before using any supplement or remedy.
