The Use of Evening Primrose Oil for Cervical Ripening in Low-Risk Women with Term Pregnancy: A Randomized Double-Blinded Controlled Trial

Abstract

Background: Several methods have been developed for cervical ripening. The data regarding the efficiency of evening primrose oil (EPO) are inconsistent. The purpose of this study was to investigate the outcomes of EPO use on cervical ripening in low-risk women with term pregnancy. Patients and Methods: Low-risk term pregnant women referred to the obstetrics clinic of Imam Hossein Hospital in Tehran who were eligible according to the inclusion were randomized either to the case or control group. The case group received 1,000 mg vaginal EPO capsule, and the other group received a vaginal placebo capsule daily, similar to the original drug. The primary outcome was Bishop score, while the duration of labor phases and the inducing procedures were the secondary outcomes. Results: Forty-eight participants were randomized to each group and were considered for data analysis. Although Bishop score was not statistically different before the intervention, it was significantly higher in case group compared to the placebo group after the intervention (EPO = 5.83 ± 1.68, placebo = 5.19 ± 1.52, p value = 0.002). Four participants in the case group and two in the control group underwent cesarean section (p value = 0.677). The need for labor induction was significantly higher in the placebo group than EPO group (oxytocin injection: 10.4% vs. 31.3%, p value = 0.012, amniotomy: 75% vs. 41.7, p value = 0.001). Conclusion: The vaginal use of EPO could be considered as a safe and efficient approach for cervical ripening in low-risk term pregnant women.