Evening Primrose Oil in Pregnancy & Birth
Evening primrose (Oenothera biennis) is an herb native to North and South America, and now widespread throughout Europe and parts of Asia, and is so named because its yellow blossoms open only in the evening. It is also known as tree primrose, sun cups, sun drops, king’s cure all, fever plant, evening star and night-willow herb. EPO is obtained through cold expression or solvent extraction from the seeds. An extraordinarily rich source of Omega-6 essential fatty acids, the plant oil contains roughly 65-70% linoleic acid and seven to 14% gamma linoleic acid (GLA), the latter of which is a considered the active ingredient in EPO. GLA is the precursor to prostaglandins E1 and E2, which are thought to be the cause of the ripening of the cervix.
Preparations of EPO are often taken orally, and have been used in the treatment of disorders characterized by chronic inflammation such as rheumatoid arthritis, PCOS, PMS, and eczema, with research being done into other applications as well. Most studies regarding the use of EPO in the third trimester of pregnancy have involved oral preparations, up until now.
Interestingly, an analysis of the EPO and pregnancy related studies that are available appear to point to the route of prescription (i.e. orally vs. vaginally) as being the major distinguishing factor between favorable results and unfavorable results in EPO use. Care to get a quick run through on this discussion? Keep reading!
Oral Route In the aforementioned 1999 EPO study, which was published by Devin Johnson as an observational study looking retrospectively at women receiving care in a birth center in the US, 54 low-risk primi para mothers took EPO capsules orally during pregnancy. Starting at 37 weeks, the women took 500mg EPO three times daily and then tapered down to 500mg a day until labor began. These 54 participants were compared to 54 other women who took nothing for birth preparation. Johnson found that the women who took EPO ended up with longer labors (by 3 hours) than the control group, as well as a trend toward increased labor complications such as prolonged rupture of membranes, Pitocin augmentation, arrest of descent and vacuum extraction.
In 2008, there was one case report of an otherwise-healthy newborn with small bruises that was born to a mother who had been taking red raspberry leaf tea and 13,500mg EPO vaginally and orally to ripen her cervix for labor. The bruises resolved after 5 days. This is the only case report that suggests a possible adverse reaction to EPO, so we can’t assume that the EPO was, in fact, the cause of the skin issue.
The most recent study we have on oral EPO use is from 2018, when Kalati et al, published a triple blind placebo controlled randomized clinical trial that analyzed the effect of EPO use on the length of pregnancy and labor. Participants were low-risk, first time mothers at 40 weeks gestation carrying single headfirst babies. They were all in very good health, had Bishop scores of less than four, and an estimated fetal weight of 2,500 and 4,000 grams. The EPO group had 40 women who each received 1,000mg of EPO twice daily for seven days, while the control group was another 40 women who each received a placebo. The results of the study were that was no difference in any way – gestational age of the baby at birth, improvement in Bishop score, need for induction or augmentation or labor, or length of labor – between the two groups. It should be noted that in this study, the participants only took the EPO for a week before delivery (since they were starting at 40 weeks of pregnancy), and that half of the women in the EPO group took capsules for less than five days before going into labor.
Vaginal Route Najafi et al, conducted a double blind randomized controlled trial in 2019 in Iran on vaginal EPO use in pregnancy. 86 first-time healthy mothers between the ages of 18 and 35 participated, each 38 weeks pregnant with a single baby, with an intact amniotic sac and none experiencing contractions. Women who were using other methods to facilitate cervical ripening such as having intercourse or taking laxatives or other herbs were excluded from the trial. Half of the participants received capsules of 1,000mg of EPO to insert vaginally at night every night up until birth, while the other half received a placebo with the same instructions. There was a significant difference between the groups in terms of Bishop’s score – 7.83 in the EPO group vs. 4.46 in the placebo group – meaning cervical dilation, effacement, position, consistency and fetal station were all much superior in the EPO group. The same was true for the average length of labor (Four to five hours for the EPO group vs. eight to nine in the control group), cesarean rate (21% vs. 47%), and use of Pitocin to induce labor (29% vs. 62%). The authors concluded, “according to the results of the present study, vaginal capsules of evening primrose oil could be an effective, safe, affordable, and without the necessity of being hospitalized, method to achieve cervical ripening.”
The only other study we have on vaginal use of EPO in pregnancy is another randomized controlled trial from Iran, looking at the effects of EPO on cervical ripening for first time mothers who had gone past their due dates. Conducted by Shahali in 2018, only the abstract is available in English so we cannot analyze the full study. However, the results were significant. 60 pregnant women participated, half of which received one EPO capsule at 1,000mg and the other half, a placebo. Both groups inserted the capsules vaginally. Length of active labor, pain scores and blood loss were the same in both groups, but the length of the early phase of labor and the average Bishop’s score were greatly improved in the EPO group.
Wrapping it Up Although the medical literature on EPO is not extensive, what we have does appear to suggest that taking it orally may have an effect on both mother and baby that is, at best, benign, but at worst, risky and injurious – and these dangers are completely avoidable simply by changing the route of prescription. However, this information is not widespread. From what I gathered in online research, it is fairly common for midwives to encourage their clients to take EPO orally, either solely or in tandem with instructions to take it vaginally if desired. Especially since pregnancy is such a delicate time in the life of a mother and her child, when ensuring the highest standard of care and nurture is imperative, it is interesting to consider how much this newer research may prevent unnecessary complications from arising during birthing experiences.
Share your thoughts! Did this research change your thoughts on EPO use? Want to add to the discussion? I'd love to hear from you in the comments. :)
Sources
1 https://pubmed.ncbi.nlm.nih.gov/10380450/
2 https://www.aafp.org/afp/2009/1215/p1405.html
3 https://evidencebasedbirth.com/evidence-on-evening-primrose-oil-epo/
4 Dove, D., & Johnson, P. (1999). Oral evening primrose oil: its effect on length of pregnancy and selected intrapartum outcomes in low-risk nulliparous women. J Nurse Midwifery, 44(3), 320-324.
5 Kalati, M., Kashanian, M., Jahdi, F., et al. (2018). Evening primrose oil and labour, is it effective? A randomised clinical trial. J Obstet Gynaecol. 38(4), 488 -492.
6 This refers to a method of assessing the readiness of the cervix for birth – including dilation, effacement, thinning of the cervix, position and consistency of the cervix, and station of the baby. The lower the Bishop score, the less favorable it is for a mother who is about to be induced.
7 Najafi, M., Loripoor, M., Saghafi, Z., et al. (2019). The effect of vaginal evening primrose on the Bishop score of term nulliparous women. NPT. 6(4), 202-211.
8 Shahali, S., Khatami, F., Abbaspoor, Z., et al. (2018) The effect of vaginal evening primrose capsule on cervical ripening in nulliparous women with post-term pregnancy: A clinical trial. The Iranian Journal of Obstetrics, Gynecology and Infertility, 21 (8), 30-38. [English Abstract Only].
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