Evening Primrose Oil for Cervical Priming: Not Recommended
Evening primrose oil should not be used for cervical ripening prior to gynecological procedures or labor induction, as current evidence shows it is ineffective for labor induction and its use during pregnancy should be avoided. 1
Evidence Against Use in Labor Induction
The most recent systematic review and meta-analysis demonstrates no significant benefit of evening primrose oil for cervical ripening:
Meta-analysis of four randomized trials found no significant difference in Bishop score improvement between evening primrose oil and control groups (SMD: 0.27,95% CI: -0.41,0.96, p = .43), with high heterogeneity (I² = 91.4%). 2
A retrospective study of 108 nulliparous women found that oral evening primrose oil from 37 weeks until birth did not shorten gestation or decrease labor length. More concerning, it was associated with increased rates of prolonged rupture of membranes, oxytocin augmentation, arrest of descent, and vacuum extraction. 3
The British Association of Dermatologists and Royal College of Physicians state that evidence for therapeutic value of evening primrose oil remains inconclusive for most conditions, with limited scientific support. 4
Alternative for Gynecological Procedures
For non-pregnant patients undergoing hysteroscopy or dilation and curettage, one small trial (n=40) suggested vaginal evening primrose oil 2000 mg may be more effective than misoprostol 200 μg for cervical ripening (mean dilator size 7.30 vs 5.25, p<.001) with less pain. 5 However, this is a single small study and misoprostol remains the evidence-based standard for cervical priming in gynecological procedures. 6
Recommended Alternatives
For Labor Induction
When cervical ripening is needed before labor induction, use proven agents rather than evening primrose oil:
- Misoprostol is the most studied cervical primer, though routine use for IUD placement is not supported due to side effects and limited pain reduction benefit. 6
- For failed IUD placement attempts or known cervical stenosis, vaginal misoprostol 200 μg at 10 and 4 hours prior improved successful placement. 6
For Gynecological Procedures
- Misoprostol remains the standard for cervical priming before hysteroscopy or dilation and curettage, despite its side effect profile. 6
- Consider mechanical dilation methods as alternatives when pharmacologic agents are contraindicated.
Safety Concerns
The use of evening primrose oil during pregnancy is not supported in the literature and should be avoided. 1 The potential for adverse outcomes including prolonged rupture of membranes and increased operative interventions outweighs any theoretical benefit. 3